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From cmcc...@apache.org
Subject [2/3] hadoop git commit: HDFS-9080. Update htrace version to 4.0.1 (cmccabe)
Date Mon, 28 Sep 2015 15:19:52 GMT
http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
index 7cfc854..80950a9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
@@ -77,6 +77,7 @@ import org.apache.hadoop.fs.FileEncryptionInfo;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.FsServerDefaults;
 import org.apache.hadoop.fs.FsStatus;
+import org.apache.hadoop.fs.FsTracer;
 import org.apache.hadoop.fs.HdfsBlockLocation;
 import org.apache.hadoop.fs.InvalidPathException;
 import org.apache.hadoop.fs.MD5MD5CRC32CastagnoliFileChecksum;
@@ -172,24 +173,19 @@ import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.SecretManager.InvalidToken;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenRenewer;
-import org.apache.hadoop.tracing.SpanReceiverHost;
-import org.apache.hadoop.tracing.TraceUtils;
 import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.DataChecksum.Type;
 import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.SamplerBuilder;
-import org.apache.htrace.Span;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.TraceScope;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.common.net.InetAddresses;
+import org.apache.htrace.core.Tracer;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -212,6 +208,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public static final long SERVER_DEFAULTS_VALIDITY_PERIOD = 60 * 60 * 1000L; // 1 hour
 
   private final Configuration conf;
+  private final Tracer tracer;
   private final DfsClientConf dfsClientConf;
   final ClientProtocol namenode;
   /* The service used for delegation tokens */
@@ -238,7 +235,6 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   private static final DFSHedgedReadMetrics HEDGED_READ_METRIC =
       new DFSHedgedReadMetrics();
   private static ThreadPoolExecutor HEDGED_READ_THREAD_POOL;
-  private final Sampler<?> traceSampler;
   private final int smallBufferSize;
 
   public DfsClientConf getConf() {
@@ -302,11 +298,8 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public DFSClient(URI nameNodeUri, ClientProtocol rpcNamenode,
       Configuration conf, FileSystem.Statistics stats)
     throws IOException {
-    SpanReceiverHost.get(conf, HdfsClientConfigKeys.DFS_CLIENT_HTRACE_PREFIX);
-    traceSampler = new SamplerBuilder(TraceUtils.
-        wrapHadoopConf(HdfsClientConfigKeys.DFS_CLIENT_HTRACE_PREFIX, conf))
-        .build();
     // Copy only the required DFSClient configuration
+    this.tracer = FsTracer.get(conf);
     this.dfsClientConf = new DfsClientConf(conf);
     this.conf = conf;
     this.stats = stats;
@@ -628,7 +621,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#getPreferredBlockSize(String)
    */
   public long getBlockSize(String f) throws IOException {
-    TraceScope scope = getPathTraceScope("getBlockSize", f);
+    TraceScope scope = newPathTraceScope("getBlockSize", f);
     try {
       return namenode.getPreferredBlockSize(f);
     } catch (IOException ie) {
@@ -670,7 +663,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer)
       throws IOException {
     assert dtService != null;
-    TraceScope scope = Trace.startSpan("getDelegationToken", traceSampler);
+    TraceScope scope = tracer.newScope("getDelegationToken");
     try {
       Token<DelegationTokenIdentifier> token =
         namenode.getDelegationToken(renewer);
@@ -826,7 +819,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   @VisibleForTesting
   public LocatedBlocks getLocatedBlocks(String src, long start, long length)
       throws IOException {
-    TraceScope scope = getPathTraceScope("getBlockLocations", src);
+    TraceScope scope = newPathTraceScope("getBlockLocations", src);
     try {
       return callGetBlockLocations(namenode, src, start, length);
     } finally {
@@ -858,7 +851,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   boolean recoverLease(String src) throws IOException {
     checkOpen();
 
-    TraceScope scope = getPathTraceScope("recoverLease", src);
+    TraceScope scope = newPathTraceScope("recoverLease", src);
     try {
       return namenode.recoverLease(src, clientName);
     } catch (RemoteException re) {
@@ -884,7 +877,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public BlockLocation[] getBlockLocations(String src, long start, 
         long length) throws IOException, UnresolvedLinkException {
-    TraceScope scope = getPathTraceScope("getBlockLocations", src);
+    TraceScope scope = newPathTraceScope("getBlockLocations", src);
     try {
       LocatedBlocks blocks = getLocatedBlocks(src, start, length);
       BlockLocation[] locations =  DFSUtilClient.locatedBlocks2Locations(blocks);
@@ -950,14 +943,14 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
         
     // Make RPCs to the datanodes to get volume locations for its replicas
     TraceScope scope =
-      Trace.startSpan("getBlockStorageLocations", traceSampler);
+      tracer.newScope("getBlockStorageLocations");
     Map<DatanodeInfo, HdfsBlocksMetadata> metadatas;
     try {
       metadatas = BlockStorageLocationUtil.
           queryDatanodesForHdfsBlocksMetadata(conf, datanodeBlocks,
               getConf().getFileBlockStorageLocationsNumThreads(),
               getConf().getFileBlockStorageLocationsTimeoutMs(),
-              getConf().isConnectToDnViaHostname());
+              getConf().isConnectToDnViaHostname(), tracer, scope.getSpanId());
       if (LOG.isTraceEnabled()) {
         LOG.trace("metadata returned: "
             + Joiner.on("\n").withKeyValueSeparator("=").join(metadatas));
@@ -983,7 +976,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   private KeyVersion decryptEncryptedDataEncryptionKey(FileEncryptionInfo
       feInfo) throws IOException {
-    TraceScope scope = Trace.startSpan("decryptEDEK", traceSampler);
+    TraceScope scope = tracer.newScope("decryptEDEK");
     try {
       KeyProvider provider = getKeyProvider();
       if (provider == null) {
@@ -1139,7 +1132,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       throws IOException, UnresolvedLinkException {
     checkOpen();
     //    Get block info from namenode
-    TraceScope scope = getPathTraceScope("newDFSInputStream", src);
+    TraceScope scope = newPathTraceScope("newDFSInputStream", src);
     try {
       return new DFSInputStream(this, src, verifyChecksum, null);
     } finally {
@@ -1384,7 +1377,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void createSymlink(String target, String link, boolean createParent)
       throws IOException {
-    TraceScope scope = getPathTraceScope("createSymlink", target);
+    TraceScope scope = newPathTraceScope("createSymlink", target);
     try {
       final FsPermission dirPerm = applyUMask(null);
       namenode.createSymlink(target, link, dirPerm, createParent);
@@ -1410,7 +1403,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public String getLinkTarget(String path) throws IOException { 
     checkOpen();
-    TraceScope scope = getPathTraceScope("getLinkTarget", path);
+    TraceScope scope = newPathTraceScope("getLinkTarget", path);
     try {
       return namenode.getLinkTarget(path);
     } catch (RemoteException re) {
@@ -1506,7 +1499,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public boolean setReplication(String src, short replication)
       throws IOException {
-    TraceScope scope = getPathTraceScope("setReplication", src);
+    TraceScope scope = newPathTraceScope("setReplication", src);
     try {
       return namenode.setReplication(src, replication);
     } catch(RemoteException re) {
@@ -1529,7 +1522,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void setStoragePolicy(String src, String policyName)
       throws IOException {
-    TraceScope scope = getPathTraceScope("setStoragePolicy", src);
+    TraceScope scope = newPathTraceScope("setStoragePolicy", src);
     try {
       namenode.setStoragePolicy(src, policyName);
     } catch (RemoteException e) {
@@ -1550,7 +1543,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public BlockStoragePolicy getStoragePolicy(String path) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getStoragePolicy", path);
+    TraceScope scope = newPathTraceScope("getStoragePolicy", path);
     try {
       return namenode.getStoragePolicy(path);
     } catch (RemoteException e) {
@@ -1567,7 +1560,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @return All the existing storage policies
    */
   public BlockStoragePolicy[] getStoragePolicies() throws IOException {
-    TraceScope scope = Trace.startSpan("getStoragePolicies", traceSampler);
+    TraceScope scope = tracer.newScope("getStoragePolicies");
     try {
       return namenode.getStoragePolicies();
     } finally {
@@ -1583,7 +1576,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   @Deprecated
   public boolean rename(String src, String dst) throws IOException {
     checkOpen();
-    TraceScope scope = getSrcDstTraceScope("rename", src, dst);
+    TraceScope scope = newSrcDstTraceScope("rename", src, dst);
     try {
       return namenode.rename(src, dst);
     } catch(RemoteException re) {
@@ -1604,7 +1597,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void concat(String trg, String [] srcs) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("concat", traceSampler);
+    TraceScope scope = tracer.newScope("concat");
     try {
       namenode.concat(trg, srcs);
     } catch(RemoteException re) {
@@ -1622,7 +1615,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void rename(String src, String dst, Options.Rename... options)
       throws IOException {
     checkOpen();
-    TraceScope scope = getSrcDstTraceScope("rename2", src, dst);
+    TraceScope scope = newSrcDstTraceScope("rename2", src, dst);
     try {
       namenode.rename2(src, dst, options);
     } catch(RemoteException re) {
@@ -1651,11 +1644,14 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       throw new HadoopIllegalArgumentException(
           "Cannot truncate to a negative file size: " + newLength + ".");
     }
+    TraceScope scope = newPathTraceScope("truncate", src);
     try {
       return namenode.truncate(src, newLength, clientName);
     } catch (RemoteException re) {
       throw re.unwrapRemoteException(AccessControlException.class,
           UnresolvedPathException.class);
+    } finally {
+      scope.close();
     }
   }
 
@@ -1678,7 +1674,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public boolean delete(String src, boolean recursive) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("delete", src);
+    TraceScope scope = newPathTraceScope("delete", src);
     try {
       return namenode.delete(src, recursive);
     } catch(RemoteException re) {
@@ -1720,7 +1716,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public DirectoryListing listPaths(String src,  byte[] startAfter,
       boolean needLocation) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("listPaths", src);
+    TraceScope scope = newPathTraceScope("listPaths", src);
     try {
       return namenode.getListing(src, startAfter, needLocation);
     } catch(RemoteException re) {
@@ -1742,7 +1738,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public HdfsFileStatus getFileInfo(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getFileInfo", src);
+    TraceScope scope = newPathTraceScope("getFileInfo", src);
     try {
       return namenode.getFileInfo(src);
     } catch(RemoteException re) {
@@ -1760,7 +1756,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public boolean isFileClosed(String src) throws IOException{
     checkOpen();
-    TraceScope scope = getPathTraceScope("isFileClosed", src);
+    TraceScope scope = newPathTraceScope("isFileClosed", src);
     try {
       return namenode.isFileClosed(src);
     } catch(RemoteException re) {
@@ -1782,7 +1778,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public HdfsFileStatus getFileLinkInfo(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getFileLinkInfo", src);
+    TraceScope scope = newPathTraceScope("getFileLinkInfo", src);
     try {
       return namenode.getFileLinkInfo(src);
     } catch(RemoteException re) {
@@ -2085,7 +2081,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void setPermission(String src, FsPermission permission)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setPermission", src);
+    TraceScope scope = newPathTraceScope("setPermission", src);
     try {
       namenode.setPermission(src, permission);
     } catch(RemoteException re) {
@@ -2110,7 +2106,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void setOwner(String src, String username, String groupname)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setOwner", src);
+    TraceScope scope = newPathTraceScope("setOwner", src);
     try {
       namenode.setOwner(src, username, groupname);
     } catch(RemoteException re) {
@@ -2126,7 +2122,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   private long[] callGetStats() throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getStats", traceSampler);
+    TraceScope scope = tracer.newScope("getStats");
     try {
       return namenode.getStats();
     } finally {
@@ -2185,7 +2181,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
                                                  String cookie)
         throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("listCorruptFileBlocks", path);
+    TraceScope scope = newPathTraceScope("listCorruptFileBlocks", path);
     try {
       return namenode.listCorruptFileBlocks(path, cookie);
     } finally {
@@ -2196,7 +2192,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public DatanodeInfo[] datanodeReport(DatanodeReportType type)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("datanodeReport", traceSampler);
+    TraceScope scope = tracer.newScope("datanodeReport");
     try {
       return namenode.getDatanodeReport(type);
     } finally {
@@ -2208,7 +2204,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       DatanodeReportType type) throws IOException {
     checkOpen();
     TraceScope scope =
-        Trace.startSpan("datanodeStorageReport", traceSampler);
+        tracer.newScope("datanodeStorageReport");
     try {
       return namenode.getDatanodeStorageReport(type);
     } finally {
@@ -2238,7 +2234,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public boolean setSafeMode(SafeModeAction action, boolean isChecked) throws IOException{
     TraceScope scope =
-        Trace.startSpan("setSafeMode", traceSampler);
+        tracer.newScope("setSafeMode");
     try {
       return namenode.setSafeMode(action, isChecked);
     } finally {
@@ -2257,7 +2253,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public String createSnapshot(String snapshotRoot, String snapshotName)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("createSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("createSnapshot");
     try {
       return namenode.createSnapshot(snapshotRoot, snapshotName);
     } catch(RemoteException re) {
@@ -2279,7 +2275,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void deleteSnapshot(String snapshotRoot, String snapshotName)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("deleteSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("deleteSnapshot");
     try {
       namenode.deleteSnapshot(snapshotRoot, snapshotName);
     } catch(RemoteException re) {
@@ -2300,7 +2296,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void renameSnapshot(String snapshotDir, String snapshotOldName,
       String snapshotNewName) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("renameSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("renameSnapshot");
     try {
       namenode.renameSnapshot(snapshotDir, snapshotOldName, snapshotNewName);
     } catch(RemoteException re) {
@@ -2319,8 +2315,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getSnapshottableDirListing",
-        traceSampler);
+    TraceScope scope = tracer.newScope("getSnapshottableDirListing");
     try {
       return namenode.getSnapshottableDirListing();
     } catch(RemoteException re) {
@@ -2337,7 +2332,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void allowSnapshot(String snapshotRoot) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("allowSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("allowSnapshot");
     try {
       namenode.allowSnapshot(snapshotRoot);
     } catch (RemoteException re) {
@@ -2354,7 +2349,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void disallowSnapshot(String snapshotRoot) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("disallowSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("disallowSnapshot");
     try {
       namenode.disallowSnapshot(snapshotRoot);
     } catch (RemoteException re) {
@@ -2372,7 +2367,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public SnapshotDiffReport getSnapshotDiffReport(String snapshotDir,
       String fromSnapshot, String toSnapshot) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getSnapshotDiffReport", traceSampler);
+    TraceScope scope = tracer.newScope("getSnapshotDiffReport");
     try {
       return namenode.getSnapshotDiffReport(snapshotDir,
           fromSnapshot, toSnapshot);
@@ -2386,7 +2381,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public long addCacheDirective(
       CacheDirectiveInfo info, EnumSet<CacheFlag> flags) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("addCacheDirective", traceSampler);
+    TraceScope scope = tracer.newScope("addCacheDirective");
     try {
       return namenode.addCacheDirective(info, flags);
     } catch (RemoteException re) {
@@ -2399,7 +2394,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void modifyCacheDirective(
       CacheDirectiveInfo info, EnumSet<CacheFlag> flags) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("modifyCacheDirective", traceSampler);
+    TraceScope scope = tracer.newScope("modifyCacheDirective");
     try {
       namenode.modifyCacheDirective(info, flags);
     } catch (RemoteException re) {
@@ -2412,7 +2407,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void removeCacheDirective(long id)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeCacheDirective", traceSampler);
+    TraceScope scope = tracer.newScope("removeCacheDirective");
     try {
       namenode.removeCacheDirective(id);
     } catch (RemoteException re) {
@@ -2424,12 +2419,12 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   
   public RemoteIterator<CacheDirectiveEntry> listCacheDirectives(
       CacheDirectiveInfo filter) throws IOException {
-    return new CacheDirectiveIterator(namenode, filter, traceSampler);
+    return new CacheDirectiveIterator(namenode, filter, tracer);
   }
 
   public void addCachePool(CachePoolInfo info) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("addCachePool", traceSampler);
+    TraceScope scope = tracer.newScope("addCachePool");
     try {
       namenode.addCachePool(info);
     } catch (RemoteException re) {
@@ -2441,7 +2436,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void modifyCachePool(CachePoolInfo info) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("modifyCachePool", traceSampler);
+    TraceScope scope = tracer.newScope("modifyCachePool");
     try {
       namenode.modifyCachePool(info);
     } catch (RemoteException re) {
@@ -2453,7 +2448,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeCachePool(String poolName) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeCachePool", traceSampler);
+    TraceScope scope = tracer.newScope("removeCachePool");
     try {
       namenode.removeCachePool(poolName);
     } catch (RemoteException re) {
@@ -2464,7 +2459,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   }
 
   public RemoteIterator<CachePoolEntry> listCachePools() throws IOException {
-    return new CachePoolIterator(namenode, traceSampler);
+    return new CachePoolIterator(namenode, tracer);
   }
 
   /**
@@ -2473,7 +2468,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#saveNamespace()
    */
   void saveNamespace() throws AccessControlException, IOException {
-    TraceScope scope = Trace.startSpan("saveNamespace", traceSampler);
+    TraceScope scope = tracer.newScope("saveNamespace");
     try {
       namenode.saveNamespace();
     } catch(RemoteException re) {
@@ -2490,7 +2485,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#rollEdits()
    */
   long rollEdits() throws AccessControlException, IOException {
-    TraceScope scope = Trace.startSpan("rollEdits", traceSampler);
+    TraceScope scope = tracer.newScope("rollEdits");
     try {
       return namenode.rollEdits();
     } catch(RemoteException re) {
@@ -2512,7 +2507,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   boolean restoreFailedStorage(String arg)
       throws AccessControlException, IOException{
-    TraceScope scope = Trace.startSpan("restoreFailedStorage", traceSampler);
+    TraceScope scope = tracer.newScope("restoreFailedStorage");
     try {
       return namenode.restoreFailedStorage(arg);
     } finally {
@@ -2528,7 +2523,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#refreshNodes()
    */
   public void refreshNodes() throws IOException {
-    TraceScope scope = Trace.startSpan("refreshNodes", traceSampler);
+    TraceScope scope = tracer.newScope("refreshNodes");
     try {
       namenode.refreshNodes();
     } finally {
@@ -2542,7 +2537,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#metaSave(String)
    */
   public void metaSave(String pathname) throws IOException {
-    TraceScope scope = Trace.startSpan("metaSave", traceSampler);
+    TraceScope scope = tracer.newScope("metaSave");
     try {
       namenode.metaSave(pathname);
     } finally {
@@ -2559,7 +2554,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#setBalancerBandwidth(long)
    */
   public void setBalancerBandwidth(long bandwidth) throws IOException {
-    TraceScope scope = Trace.startSpan("setBalancerBandwidth", traceSampler);
+    TraceScope scope = tracer.newScope("setBalancerBandwidth");
     try {
       namenode.setBalancerBandwidth(bandwidth);
     } finally {
@@ -2571,7 +2566,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#finalizeUpgrade()
    */
   public void finalizeUpgrade() throws IOException {
-    TraceScope scope = Trace.startSpan("finalizeUpgrade", traceSampler);
+    TraceScope scope = tracer.newScope("finalizeUpgrade");
     try {
       namenode.finalizeUpgrade();
     } finally {
@@ -2580,7 +2575,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   }
 
   RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action) throws IOException {
-    TraceScope scope = Trace.startSpan("rollingUpgrade", traceSampler);
+    TraceScope scope = tracer.newScope("rollingUpgrade");
     try {
       return namenode.rollingUpgrade(action);
     } finally {
@@ -2638,7 +2633,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
     if(LOG.isDebugEnabled()) {
       LOG.debug(src + ": masked=" + absPermission);
     }
-    TraceScope scope = Trace.startSpan("mkdir", traceSampler);
+    TraceScope scope = tracer.newScope("mkdir");
     try {
       return namenode.mkdirs(src, absPermission, createParent);
     } catch(RemoteException re) {
@@ -2665,7 +2660,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    * @see ClientProtocol#getContentSummary(String)
    */
   ContentSummary getContentSummary(String src) throws IOException {
-    TraceScope scope = getPathTraceScope("getContentSummary", src);
+    TraceScope scope = newPathTraceScope("getContentSummary", src);
     try {
       return namenode.getContentSummary(src);
     } catch(RemoteException re) {
@@ -2693,7 +2688,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
                                          storagespaceQuota);
                                          
     }
-    TraceScope scope = getPathTraceScope("setQuota", src);
+    TraceScope scope = newPathTraceScope("setQuota", src);
     try {
       // Pass null as storage type for traditional namespace/storagespace quota.
       namenode.setQuota(src, namespaceQuota, storagespaceQuota, null);
@@ -2728,7 +2723,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       throw new IllegalArgumentException("Don't support Quota for storage type : "
         + type.toString());
     }
-    TraceScope scope = getPathTraceScope("setQuotaByStorageType", src);
+    TraceScope scope = newPathTraceScope("setQuotaByStorageType", src);
     try {
       namenode.setQuota(src, HdfsConstants.QUOTA_DONT_SET, quota, type);
     } catch (RemoteException re) {
@@ -2748,7 +2743,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void setTimes(String src, long mtime, long atime) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setTimes", src);
+    TraceScope scope = newPathTraceScope("setTimes", src);
     try {
       namenode.setTimes(src, mtime, atime);
     } catch(RemoteException re) {
@@ -2809,7 +2804,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void modifyAclEntries(String src, List<AclEntry> aclSpec)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("modifyAclEntries", src);
+    TraceScope scope = newPathTraceScope("modifyAclEntries", src);
     try {
       namenode.modifyAclEntries(src, aclSpec);
     } catch(RemoteException re) {
@@ -2828,7 +2823,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void removeAclEntries(String src, List<AclEntry> aclSpec)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeAclEntries", traceSampler);
+    TraceScope scope = tracer.newScope("removeAclEntries");
     try {
       namenode.removeAclEntries(src, aclSpec);
     } catch(RemoteException re) {
@@ -2846,7 +2841,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeDefaultAcl(String src) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeDefaultAcl", traceSampler);
+    TraceScope scope = tracer.newScope("removeDefaultAcl");
     try {
       namenode.removeDefaultAcl(src);
     } catch(RemoteException re) {
@@ -2864,7 +2859,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeAcl(String src) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeAcl", traceSampler);
+    TraceScope scope = tracer.newScope("removeAcl");
     try {
       namenode.removeAcl(src);
     } catch(RemoteException re) {
@@ -2882,7 +2877,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void setAcl(String src, List<AclEntry> aclSpec) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("setAcl", traceSampler);
+    TraceScope scope = tracer.newScope("setAcl");
     try {
       namenode.setAcl(src, aclSpec);
     } catch(RemoteException re) {
@@ -2900,7 +2895,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public AclStatus getAclStatus(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getAclStatus", src);
+    TraceScope scope = newPathTraceScope("getAclStatus", src);
     try {
       return namenode.getAclStatus(src);
     } catch(RemoteException re) {
@@ -2916,7 +2911,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void createEncryptionZone(String src, String keyName)
     throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("createEncryptionZone", src);
+    TraceScope scope = newPathTraceScope("createEncryptionZone", src);
     try {
       namenode.createEncryptionZone(src, keyName);
     } catch (RemoteException re) {
@@ -2931,7 +2926,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public EncryptionZone getEZForPath(String src)
           throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getEZForPath", src);
+    TraceScope scope = newPathTraceScope("getEZForPath", src);
     try {
       return namenode.getEZForPath(src);
     } catch (RemoteException re) {
@@ -2945,13 +2940,13 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public RemoteIterator<EncryptionZone> listEncryptionZones()
       throws IOException {
     checkOpen();
-    return new EncryptionZoneIterator(namenode, traceSampler);
+    return new EncryptionZoneIterator(namenode, tracer);
   }
 
   public void setXAttr(String src, String name, byte[] value, 
       EnumSet<XAttrSetFlag> flag) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setXAttr", src);
+    TraceScope scope = newPathTraceScope("setXAttr", src);
     try {
       namenode.setXAttr(src, XAttrHelper.buildXAttr(name, value), flag);
     } catch (RemoteException re) {
@@ -2968,7 +2963,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   
   public byte[] getXAttr(String src, String name) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getXAttr", src);
+    TraceScope scope = newPathTraceScope("getXAttr", src);
     try {
       final List<XAttr> xAttrs = XAttrHelper.buildXAttrAsList(name);
       final List<XAttr> result = namenode.getXAttrs(src, xAttrs);
@@ -2984,7 +2979,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   
   public Map<String, byte[]> getXAttrs(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getXAttrs", src);
+    TraceScope scope = newPathTraceScope("getXAttrs", src);
     try {
       return XAttrHelper.buildXAttrMap(namenode.getXAttrs(src, null));
     } catch(RemoteException re) {
@@ -2999,7 +2994,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public Map<String, byte[]> getXAttrs(String src, List<String> names) 
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getXAttrs", src);
+    TraceScope scope = newPathTraceScope("getXAttrs", src);
     try {
       return XAttrHelper.buildXAttrMap(namenode.getXAttrs(
           src, XAttrHelper.buildXAttrs(names)));
@@ -3015,7 +3010,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public List<String> listXAttrs(String src)
           throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("listXAttrs", src);
+    TraceScope scope = newPathTraceScope("listXAttrs", src);
     try {
       final Map<String, byte[]> xattrs =
         XAttrHelper.buildXAttrMap(namenode.listXAttrs(src));
@@ -3031,7 +3026,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeXAttr(String src, String name) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("removeXAttr", src);
+    TraceScope scope = newPathTraceScope("removeXAttr", src);
     try {
       namenode.removeXAttr(src, XAttrHelper.buildXAttr(name));
     } catch(RemoteException re) {
@@ -3048,7 +3043,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void checkAccess(String src, FsAction mode) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("checkAccess", src);
+    TraceScope scope = newPathTraceScope("checkAccess", src);
     try {
       namenode.checkAccess(src, mode);
     } catch (RemoteException re) {
@@ -3061,12 +3056,13 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   }
 
   public DFSInotifyEventInputStream getInotifyEventStream() throws IOException {
-    return new DFSInotifyEventInputStream(traceSampler, namenode);
+    return new DFSInotifyEventInputStream(namenode, tracer);
   }
 
   public DFSInotifyEventInputStream getInotifyEventStream(long lastReadTxid)
       throws IOException {
-    return new DFSInotifyEventInputStream(traceSampler, namenode, lastReadTxid);
+    return new DFSInotifyEventInputStream(namenode, tracer,
+          lastReadTxid);
   }
 
   @Override // RemotePeerFactory
@@ -3176,28 +3172,26 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
     return saslClient;
   }
 
-  TraceScope getPathTraceScope(String description, String path) {
-    TraceScope scope = Trace.startSpan(description, traceSampler);
-    Span span = scope.getSpan();
-    if (span != null) {
-      if (path != null) {
-        span.addKVAnnotation("path", path);
-      }
+  TraceScope newPathTraceScope(String description, String path) {
+    TraceScope scope = tracer.newScope(description);
+    if (path != null) {
+      scope.addKVAnnotation("path", path);
     }
     return scope;
   }
 
-  TraceScope getSrcDstTraceScope(String description, String src, String dst) {
-    TraceScope scope = Trace.startSpan(description, traceSampler);
-    Span span = scope.getSpan();
-    if (span != null) {
-      if (src != null) {
-        span.addKVAnnotation("src", src);
-      }
-      if (dst != null) {
-        span.addKVAnnotation("dst", dst);
-      }
+  TraceScope newSrcDstTraceScope(String description, String src, String dst) {
+    TraceScope scope = tracer.newScope(description);
+    if (src != null) {
+      scope.addKVAnnotation("src", src);
+    }
+    if (dst != null) {
+      scope.addKVAnnotation("dst", dst);
     }
     return scope;
   }
+
+  Tracer getTracer() {
+    return tracer;
+  }
 }

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInotifyEventInputStream.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInotifyEventInputStream.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInotifyEventInputStream.java
index 11a1d29..c98cd5f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInotifyEventInputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInotifyEventInputStream.java
@@ -26,9 +26,8 @@ import org.apache.hadoop.hdfs.inotify.EventBatchList;
 import org.apache.hadoop.hdfs.inotify.MissingEventsException;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -47,11 +46,6 @@ public class DFSInotifyEventInputStream {
   public static final Logger LOG = LoggerFactory.getLogger(
       DFSInotifyEventInputStream.class);
 
-  /**
-   * The trace sampler to use when making RPCs to the NameNode.
-   */
-  private final Sampler<?> traceSampler;
-
   private final ClientProtocol namenode;
   private Iterator<EventBatch> it;
   private long lastReadTxid;
@@ -65,20 +59,22 @@ public class DFSInotifyEventInputStream {
    */
   private Random rng = new Random();
 
+  private final Tracer tracer;
+
   private static final int INITIAL_WAIT_MS = 10;
 
-  DFSInotifyEventInputStream(Sampler<?> traceSampler, ClientProtocol namenode)
+  DFSInotifyEventInputStream(ClientProtocol namenode, Tracer tracer)
         throws IOException {
     // Only consider new transaction IDs.
-    this(traceSampler, namenode, namenode.getCurrentEditLogTxid());
+    this(namenode, tracer, namenode.getCurrentEditLogTxid());
   }
 
-  DFSInotifyEventInputStream(Sampler traceSampler, ClientProtocol namenode,
-        long lastReadTxid) throws IOException {
-    this.traceSampler = traceSampler;
+  DFSInotifyEventInputStream(ClientProtocol namenode,
+        Tracer tracer, long lastReadTxid) throws IOException {
     this.namenode = namenode;
     this.it = Iterators.emptyIterator();
     this.lastReadTxid = lastReadTxid;
+    this.tracer = tracer;
   }
 
   /**
@@ -98,8 +94,7 @@ public class DFSInotifyEventInputStream {
    * The next available batch of events will be returned.
    */
   public EventBatch poll() throws IOException, MissingEventsException {
-    TraceScope scope =
-        Trace.startSpan("inotifyPoll", traceSampler);
+    TraceScope scope = tracer.newScope("inotifyPoll");
     try {
       // need to keep retrying until the NN sends us the latest committed txid
       if (lastReadTxid == -1) {
@@ -180,7 +175,7 @@ public class DFSInotifyEventInputStream {
    */
   public EventBatch poll(long time, TimeUnit tu) throws IOException,
       InterruptedException, MissingEventsException {
-    TraceScope scope = Trace.startSpan("inotifyPollWithTimeout", traceSampler);
+    TraceScope scope = tracer.newScope("inotifyPollWithTimeout");
     EventBatch next = null;
     try {
       long initialTime = Time.monotonicNow();
@@ -217,7 +212,7 @@ public class DFSInotifyEventInputStream {
    */
   public EventBatch take() throws IOException, InterruptedException,
       MissingEventsException {
-    TraceScope scope = Trace.startSpan("inotifyTake", traceSampler);
+    TraceScope scope = tracer.newScope("inotifyTake");
     EventBatch next = null;
     try {
       int nextWaitMin = INITIAL_WAIT_MS;

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
index 139a27c..7101753 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java
@@ -55,6 +55,7 @@ import org.apache.hadoop.fs.CanUnbuffer;
 import org.apache.hadoop.fs.ChecksumException;
 import org.apache.hadoop.fs.FSInputStream;
 import org.apache.hadoop.fs.FileEncryptionInfo;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.HasEnhancedByteBufferAccess;
 import org.apache.hadoop.fs.ReadOption;
 import org.apache.hadoop.fs.StorageType;
@@ -78,9 +79,9 @@ import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.token.SecretManager.InvalidToken;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.IdentityHashStore;
-import org.apache.htrace.Span;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.SpanId;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 import com.google.common.annotations.VisibleForTesting;
 
@@ -678,6 +679,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
         setClientCacheContext(dfsClient.getClientContext()).
         setUserGroupInformation(dfsClient.ugi).
         setConfiguration(dfsClient.getConfiguration()).
+        setTracer(dfsClient.getTracer()).
         build();
   }
 
@@ -941,7 +943,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
   public synchronized int read(final byte buf[], int off, int len) throws IOException {
     ReaderStrategy byteArrayReader = new ByteArrayStrategy(buf);
     TraceScope scope =
-        dfsClient.getPathTraceScope("DFSInputStream#byteArrayRead", src);
+        dfsClient.newPathTraceScope("DFSInputStream#byteArrayRead", src);
     try {
       return readWithStrategy(byteArrayReader, off, len);
     } finally {
@@ -953,7 +955,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
   public synchronized int read(final ByteBuffer buf) throws IOException {
     ReaderStrategy byteBufferReader = new ByteBufferStrategy(buf);
     TraceScope scope =
-        dfsClient.getPathTraceScope("DFSInputStream#byteBufferRead", src);
+        dfsClient.newPathTraceScope("DFSInputStream#byteBufferRead", src);
     try {
       return readWithStrategy(byteBufferReader, 0, buf.remaining());
     } finally {
@@ -1120,14 +1122,14 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
       final ByteBuffer bb,
       final Map<ExtendedBlock, Set<DatanodeInfo>> corruptedBlockMap,
       final int hedgedReadId) {
-    final Span parentSpan = Trace.currentSpan();
+    final SpanId parentSpanId = Tracer.getCurrentSpanId();
     return new Callable<ByteBuffer>() {
       @Override
       public ByteBuffer call() throws Exception {
         byte[] buf = bb.array();
         int offset = bb.position();
-        TraceScope scope =
-            Trace.startSpan("hedgedRead" + hedgedReadId, parentSpan);
+        TraceScope scope = dfsClient.getTracer().
+            newScope("hedgedRead" + hedgedReadId, parentSpanId);
         try {
           actualGetFromOneDataNode(datanode, block, start, end, buf,
               offset, corruptedBlockMap);
@@ -1449,8 +1451,8 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
   @Override
   public int read(long position, byte[] buffer, int offset, int length)
       throws IOException {
-    TraceScope scope =
-        dfsClient.getPathTraceScope("DFSInputStream#byteArrayPread", src);
+    TraceScope scope = dfsClient.
+        newPathTraceScope("DFSInputStream#byteArrayPread", src);
     try {
       return pread(position, buffer, offset, length);
     } finally {

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
index 5466936..6872683 100755
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
@@ -32,6 +32,7 @@ import org.apache.hadoop.fs.CreateFlag;
 import org.apache.hadoop.fs.FSOutputSummer;
 import org.apache.hadoop.fs.FileAlreadyExistsException;
 import org.apache.hadoop.fs.FileEncryptionInfo;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.ParentNotDirectoryException;
 import org.apache.hadoop.fs.Syncable;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -62,9 +63,7 @@ import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.DataChecksum.Type;
 import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.TraceScope;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -227,7 +226,7 @@ public class DFSOutputStream extends FSOutputSummer
       short replication, long blockSize, Progressable progress, int buffersize,
       DataChecksum checksum, String[] favoredNodes) throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("newStreamForCreate", src);
+        dfsClient.newPathTraceScope("newStreamForCreate", src);
     try {
       HdfsFileStatus stat = null;
 
@@ -350,7 +349,7 @@ public class DFSOutputStream extends FSOutputSummer
       LocatedBlock lastBlock, HdfsFileStatus stat, DataChecksum checksum,
       String[] favoredNodes) throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("newStreamForAppend", src);
+        dfsClient.newPathTraceScope("newStreamForAppend", src);
     try {
       final DFSOutputStream out = new DFSOutputStream(dfsClient, src, flags,
           progress, lastBlock, stat, checksum, favoredNodes);
@@ -375,7 +374,7 @@ public class DFSOutputStream extends FSOutputSummer
   }
 
   protected TraceScope createWriteTraceScope() {
-    return dfsClient.getPathTraceScope("DFSOutputStream#write", src);
+    return dfsClient.newPathTraceScope("DFSOutputStream#write", src);
   }
 
   // @see FSOutputSummer#writeChunk()
@@ -495,7 +494,7 @@ public class DFSOutputStream extends FSOutputSummer
   @Override
   public void hflush() throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("hflush", src);
+        dfsClient.newPathTraceScope("hflush", src);
     try {
       flushOrSync(false, EnumSet.noneOf(SyncFlag.class));
     } finally {
@@ -506,7 +505,7 @@ public class DFSOutputStream extends FSOutputSummer
   @Override
   public void hsync() throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("hsync", src);
+        dfsClient.newPathTraceScope("hsync", src);
     try {
       flushOrSync(true, EnumSet.noneOf(SyncFlag.class));
     } finally {
@@ -529,7 +528,7 @@ public class DFSOutputStream extends FSOutputSummer
    */
   public void hsync(EnumSet<SyncFlag> syncFlags) throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("hsync", src);
+        dfsClient.newPathTraceScope("hsync", src);
     try {
       flushOrSync(true, syncFlags);
     } finally {
@@ -770,7 +769,7 @@ public class DFSOutputStream extends FSOutputSummer
   @Override
   public synchronized void close() throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("DFSOutputStream#close", src);
+        dfsClient.newPathTraceScope("DFSOutputStream#close", src);
     try {
       closeImpl();
     } finally {
@@ -799,7 +798,7 @@ public class DFSOutputStream extends FSOutputSummer
       // get last block before destroying the streamer
       ExtendedBlock lastBlock = getStreamer().getBlock();
       closeThreads(false);
-      TraceScope scope = Trace.startSpan("completeFile", Sampler.NEVER);
+      TraceScope scope = dfsClient.getTracer().newScope("completeFile");
       try {
         completeFile(lastBlock);
       } finally {

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSPacket.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSPacket.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSPacket.java
index 22055c3..9a8ca6f 100755
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSPacket.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSPacket.java
@@ -27,7 +27,9 @@ import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.datatransfer.PacketHeader;
 import org.apache.hadoop.hdfs.util.ByteArrayManager;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.Span;
+import org.apache.htrace.core.SpanId;
+import org.apache.htrace.core.TraceScope;
 
 /****************************************************************
  * DFSPacket is used by DataStreamer and DFSOutputStream.
@@ -38,7 +40,7 @@ import org.apache.htrace.Span;
 @InterfaceAudience.Private
 class DFSPacket {
   public static final long HEART_BEAT_SEQNO = -1L;
-  private static long[] EMPTY = new long[0];
+  private static SpanId[] EMPTY = new SpanId[0];
   private final long seqno; // sequence number of buffer in block
   private final long offsetInBlock; // offset in block
   private boolean syncBlock; // this packet forces the current block to disk
@@ -65,9 +67,9 @@ class DFSPacket {
   private int checksumPos;
   private final int dataStart;
   private int dataPos;
-  private long[] traceParents = EMPTY;
+  private SpanId[] traceParents = EMPTY;
   private int traceParentsUsed;
-  private Span span;
+  private TraceScope scope;
 
   /**
    * Create a new packet.
@@ -293,7 +295,10 @@ class DFSPacket {
     addTraceParent(span.getSpanId());
   }
 
-  public void addTraceParent(long id) {
+  public void addTraceParent(SpanId id) {
+    if (!id.isValid()) {
+      return;
+    }
     if (traceParentsUsed == traceParents.length) {
       int newLength = (traceParents.length == 0) ? 8 :
           traceParents.length * 2;
@@ -310,18 +315,18 @@ class DFSPacket {
    *
    * Protected by the DFSOutputStream dataQueue lock.
    */
-  public long[] getTraceParents() {
+  public SpanId[] getTraceParents() {
     // Remove duplicates from the array.
     int len = traceParentsUsed;
     Arrays.sort(traceParents, 0, len);
     int i = 0, j = 0;
-    long prevVal = 0; // 0 is not a valid span id
+    SpanId prevVal = SpanId.INVALID;
     while (true) {
       if (i == len) {
         break;
       }
-      long val = traceParents[i];
-      if (val != prevVal) {
+      SpanId val = traceParents[i];
+      if (!val.equals(prevVal)) {
         traceParents[j] = val;
         j++;
         prevVal = val;
@@ -335,11 +340,11 @@ class DFSPacket {
     return traceParents;
   }
 
-  public void setTraceSpan(Span span) {
-    this.span = span;
+  public void setTraceScope(TraceScope scope) {
+    this.scope = scope;
   }
 
-  public Span getTraceSpan() {
-    return span;
+  public TraceScope getTraceScope() {
+    return scope;
   }
 }

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java
index fb57825..6482966 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java
@@ -41,6 +41,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.StorageType;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.BlockWrite;
 import org.apache.hadoop.hdfs.client.impl.DfsClientConf;
@@ -79,12 +80,11 @@ import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.NullScope;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Span;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceInfo;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.Sampler;
+import org.apache.htrace.core.Span;
+import org.apache.htrace.core.SpanId;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
@@ -505,7 +505,7 @@ class DataStreamer extends Daemon {
   @Override
   public void run() {
     long lastPacket = Time.monotonicNow();
-    TraceScope scope = NullScope.INSTANCE;
+    TraceScope scope = null;
     while (!streamerClosed && dfsClient.clientRunning) {
       // if the Responder encountered an error, shutdown Responder
       if (errorState.hasError() && response != null) {
@@ -556,12 +556,11 @@ class DataStreamer extends Daemon {
               LOG.warn("Caught exception", e);
             }
             one = dataQueue.getFirst(); // regular data packet
-            long parents[] = one.getTraceParents();
+            SpanId[] parents = one.getTraceParents();
             if (parents.length > 0) {
-              scope = Trace.startSpan("dataStreamer", new TraceInfo(0, parents[0]));
-              // TODO: use setParents API once it's available from HTrace 3.2
-              // scope = Trace.startSpan("dataStreamer", Sampler.ALWAYS);
-              // scope.getSpan().setParents(parents);
+              scope = dfsClient.getTracer().
+                  newScope("dataStreamer", parents[0]);
+              scope.getSpan().setParents(parents);
             }
           }
         }
@@ -612,12 +611,16 @@ class DataStreamer extends Daemon {
         }
 
         // send the packet
-        Span span = null;
+        SpanId spanId = SpanId.INVALID;
         synchronized (dataQueue) {
           // move packet from dataQueue to ackQueue
           if (!one.isHeartbeatPacket()) {
-            span = scope.detach();
-            one.setTraceSpan(span);
+            if (scope != null) {
+              spanId = scope.getSpanId();
+              scope.detach();
+              one.setTraceScope(scope);
+            }
+            scope = null;
             dataQueue.removeFirst();
             ackQueue.addLast(one);
             dataQueue.notifyAll();
@@ -630,7 +633,8 @@ class DataStreamer extends Daemon {
         }
 
         // write out data to remote datanode
-        TraceScope writeScope = Trace.startSpan("writeTo", span);
+        TraceScope writeScope = dfsClient.getTracer().
+            newScope("DataStreamer#writeTo", spanId);
         try {
           one.writeTo(blockStream);
           blockStream.flush();
@@ -697,7 +701,10 @@ class DataStreamer extends Daemon {
           streamerClosed = true;
         }
       } finally {
-        scope.close();
+        if (scope != null) {
+          scope.close();
+          scope = null;
+        }
       }
     }
     closeInternal();
@@ -731,7 +738,8 @@ class DataStreamer extends Daemon {
    * @throws IOException
    */
   void waitForAckedSeqno(long seqno) throws IOException {
-    TraceScope scope = Trace.startSpan("waitForAckedSeqno", Sampler.NEVER);
+    TraceScope scope = dfsClient.getTracer().
+        newScope("waitForAckedSeqno");
     try {
       if (LOG.isDebugEnabled()) {
         LOG.debug("Waiting for ack for: " + seqno);
@@ -781,7 +789,7 @@ class DataStreamer extends Daemon {
           while (!streamerClosed && dataQueue.size() + ackQueue.size() >
               dfsClient.getConf().getWriteMaxPackets()) {
             if (firstWait) {
-              Span span = Trace.currentSpan();
+              Span span = Tracer.getCurrentSpan();
               if (span != null) {
                 span.addTimelineAnnotation("dataQueue.wait");
               }
@@ -802,7 +810,7 @@ class DataStreamer extends Daemon {
             }
           }
         } finally {
-          Span span = Trace.currentSpan();
+          Span span = Tracer.getCurrentSpan();
           if ((span != null) && (!firstWait)) {
             span.addTimelineAnnotation("end.wait");
           }
@@ -934,7 +942,7 @@ class DataStreamer extends Daemon {
       setName("ResponseProcessor for block " + block);
       PipelineAck ack = new PipelineAck();
 
-      TraceScope scope = NullScope.INSTANCE;
+      TraceScope scope = null;
       while (!responderClosed && dfsClient.clientRunning && !isLastPacketInBlock) {
         // process responses from datanodes.
         try {
@@ -1021,8 +1029,11 @@ class DataStreamer extends Daemon {
           block.setNumBytes(one.getLastByteOffsetBlock());
 
           synchronized (dataQueue) {
-            scope = Trace.continueSpan(one.getTraceSpan());
-            one.setTraceSpan(null);
+            scope = one.getTraceScope();
+            if (scope != null) {
+              scope.reattach();
+              one.setTraceScope(null);
+            }
             lastAckedSeqno = seqno;
             ackQueue.removeFirst();
             dataQueue.notifyAll();
@@ -1043,7 +1054,10 @@ class DataStreamer extends Daemon {
             responderClosed = true;
           }
         } finally {
+          if (scope != null) {
             scope.close();
+          }
+          scope = null;
         }
       }
     }
@@ -1109,11 +1123,12 @@ class DataStreamer extends Daemon {
         // a client waiting on close() will be aware that the flush finished.
         synchronized (dataQueue) {
           DFSPacket endOfBlockPacket = dataQueue.remove();  // remove the end of block packet
-          Span span = endOfBlockPacket.getTraceSpan();
-          if (span != null) {
-            // Close any trace span associated with this Packet
-            TraceScope scope = Trace.continueSpan(span);
+          // Close any trace span associated with this Packet
+          TraceScope scope = endOfBlockPacket.getTraceScope();
+          if (scope != null) {
+            scope.reattach();
             scope.close();
+            endOfBlockPacket.setTraceScope(null);
           }
           assert endOfBlockPacket.isLastPacketInBlock();
           assert lastAckedSeqno == endOfBlockPacket.getSeqno() - 1;
@@ -1741,7 +1756,7 @@ class DataStreamer extends Daemon {
   void queuePacket(DFSPacket packet) {
     synchronized (dataQueue) {
       if (packet == null) return;
-      packet.addTraceParent(Trace.currentSpan());
+      packet.addTraceParent(Tracer.getCurrentSpanId());
       dataQueue.addLast(packet);
       lastQueuedSeqno = packet.getSeqno();
       if (LOG.isDebugEnabled()) {

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader.java
index 7509da5..15a5bee 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader.java
@@ -47,9 +47,8 @@ import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -106,6 +105,8 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
   int dataLeft = 0;
   
   private final PeerCache peerCache;
+
+  private final Tracer tracer;
   
   /* FSInputChecker interface */
   
@@ -210,9 +211,8 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
   protected synchronized int readChunk(long pos, byte[] buf, int offset, 
                                        int len, byte[] checksumBuf) 
                                        throws IOException {
-    TraceScope scope =
-        Trace.startSpan("RemoteBlockReader#readChunk(" + blockId + ")",
-            Sampler.NEVER);
+    TraceScope scope = tracer.
+        newScope("RemoteBlockReader#readChunk(" + blockId + ")");
     try {
       return readChunkImpl(pos, buf, offset, len, checksumBuf);
     } finally {
@@ -346,7 +346,7 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
   private RemoteBlockReader(String file, String bpid, long blockId,
       DataInputStream in, DataChecksum checksum, boolean verifyChecksum,
       long startOffset, long firstChunkOffset, long bytesToRead, Peer peer,
-      DatanodeID datanodeID, PeerCache peerCache) {
+      DatanodeID datanodeID, PeerCache peerCache, Tracer tracer) {
     // Path is used only for printing block and file information in debug
     super(new Path("/" + Block.BLOCK_FILE_PREFIX + blockId +
                     ":" + bpid + ":of:"+ file)/*too non path-like?*/,
@@ -378,6 +378,7 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
     bytesPerChecksum = this.checksum.getBytesPerChecksum();
     checksumSize = this.checksum.getChecksumSize();
     this.peerCache = peerCache;
+    this.tracer = tracer;
   }
 
   /**
@@ -402,7 +403,8 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
                                      String clientName, Peer peer,
                                      DatanodeID datanodeID,
                                      PeerCache peerCache,
-                                     CachingStrategy cachingStrategy)
+                                     CachingStrategy cachingStrategy,
+                                     Tracer tracer)
                                        throws IOException {
     // in and out will be closed when sock is closed (by the caller)
     final DataOutputStream out =
@@ -438,7 +440,7 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
 
     return new RemoteBlockReader(file, block.getBlockPoolId(), block.getBlockId(),
         in, checksum, verifyChecksum, startOffset, firstChunkOffset, len,
-        peer, datanodeID, peerCache);
+        peer, datanodeID, peerCache, tracer);
   }
 
   @Override

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader2.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader2.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader2.java
index 5541e6d..7a7932d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader2.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader2.java
@@ -48,12 +48,11 @@ import org.apache.hadoop.hdfs.shortcircuit.ClientMmap;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.TraceScope;
 
 import com.google.common.annotations.VisibleForTesting;
 
+import org.apache.htrace.core.Tracer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -126,6 +125,8 @@ public class RemoteBlockReader2  implements BlockReader {
 
   private boolean sentStatusCode = false;
 
+  private final Tracer tracer;
+
   @VisibleForTesting
   public Peer getPeer() {
     return peer;
@@ -144,8 +145,8 @@ public class RemoteBlockReader2  implements BlockReader {
     }
 
     if (curDataSlice == null || curDataSlice.remaining() == 0 && bytesNeededToFinish > 0) {
-      TraceScope scope = Trace.startSpan(
-          "RemoteBlockReader2#readNextPacket(" + blockId + ")", Sampler.NEVER);
+      TraceScope scope = tracer.newScope(
+          "RemoteBlockReader2#readNextPacket(" + blockId + ")");
       try {
         readNextPacket();
       } finally {
@@ -172,8 +173,8 @@ public class RemoteBlockReader2  implements BlockReader {
   @Override
   public synchronized int read(ByteBuffer buf) throws IOException {
     if (curDataSlice == null || curDataSlice.remaining() == 0 && bytesNeededToFinish > 0) {
-      TraceScope scope = Trace.startSpan(
-          "RemoteBlockReader2#readNextPacket(" + blockId + ")", Sampler.NEVER);
+      TraceScope scope = tracer.newScope(
+          "RemoteBlockReader2#readNextPacket(" + blockId + ")");
       try {
         readNextPacket();
       } finally {
@@ -292,7 +293,7 @@ public class RemoteBlockReader2  implements BlockReader {
   protected RemoteBlockReader2(String file, String bpid, long blockId,
       DataChecksum checksum, boolean verifyChecksum,
       long startOffset, long firstChunkOffset, long bytesToRead, Peer peer,
-      DatanodeID datanodeID, PeerCache peerCache) {
+      DatanodeID datanodeID, PeerCache peerCache, Tracer tracer) {
     this.isLocal = DFSUtilClient.isLocalAddress(NetUtils.
         createSocketAddr(datanodeID.getXferAddr()));
     // Path is used only for printing block and file information in debug
@@ -313,6 +314,7 @@ public class RemoteBlockReader2  implements BlockReader {
     this.bytesNeededToFinish = bytesToRead + (startOffset - firstChunkOffset);
     bytesPerChecksum = this.checksum.getBytesPerChecksum();
     checksumSize = this.checksum.getChecksumSize();
+    this.tracer = tracer;
   }
 
 
@@ -407,7 +409,8 @@ public class RemoteBlockReader2  implements BlockReader {
                                      String clientName,
                                      Peer peer, DatanodeID datanodeID,
                                      PeerCache peerCache,
-                                     CachingStrategy cachingStrategy) throws IOException {
+                                     CachingStrategy cachingStrategy,
+                                     Tracer tracer) throws IOException {
     // in and out will be closed when sock is closed (by the caller)
     final DataOutputStream out = new DataOutputStream(new BufferedOutputStream(
           peer.getOutputStream()));
@@ -440,7 +443,7 @@ public class RemoteBlockReader2  implements BlockReader {
 
     return new RemoteBlockReader2(file, block.getBlockPoolId(), block.getBlockId(),
         checksum, verifyChecksum, startOffset, firstChunkOffset, len, peer,
-        datanodeID, peerCache);
+        datanodeID, peerCache, tracer);
   }
 
   static void checkSuccess(

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java
index 923cdb4..f144a55 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java
@@ -25,11 +25,10 @@ import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.BatchedRemoteIterator;
 import org.apache.hadoop.fs.InvalidRequestException;
 import org.apache.hadoop.ipc.RemoteException;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.base.Preconditions;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 /**
  * CacheDirectiveIterator is a remote iterator that iterates cache directives.
@@ -42,14 +41,14 @@ public class CacheDirectiveIterator
 
   private CacheDirectiveInfo filter;
   private final ClientProtocol namenode;
-  private final Sampler<?> traceSampler;
+  private final Tracer tracer;
 
   public CacheDirectiveIterator(ClientProtocol namenode,
-      CacheDirectiveInfo filter, Sampler<?> traceSampler) {
+      CacheDirectiveInfo filter, Tracer tracer) {
     super(0L);
     this.namenode = namenode;
     this.filter = filter;
-    this.traceSampler = traceSampler;
+    this.tracer = tracer;
   }
 
   private static CacheDirectiveInfo removeIdFromFilter(CacheDirectiveInfo filter) {
@@ -94,7 +93,7 @@ public class CacheDirectiveIterator
   public BatchedEntries<CacheDirectiveEntry> makeRequest(Long prevKey)
       throws IOException {
     BatchedEntries<CacheDirectiveEntry> entries = null;
-    TraceScope scope = Trace.startSpan("listCacheDirectives", traceSampler);
+    TraceScope scope = tracer.newScope("listCacheDirectives");
     try {
       entries = namenode.listCacheDirectives(prevKey, filter);
     } catch (IOException e) {

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CachePoolIterator.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CachePoolIterator.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CachePoolIterator.java
index e9481f7..5e2bbf2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CachePoolIterator.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CachePoolIterator.java
@@ -23,9 +23,8 @@ import java.io.IOException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.BatchedRemoteIterator;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 /**
  * CachePoolIterator is a remote iterator that iterates cache pools.
@@ -37,18 +36,18 @@ public class CachePoolIterator
     extends BatchedRemoteIterator<String, CachePoolEntry> {
 
   private final ClientProtocol namenode;
-  private final Sampler traceSampler;
+  private final Tracer tracer;
 
-  public CachePoolIterator(ClientProtocol namenode, Sampler traceSampler) {
+  public CachePoolIterator(ClientProtocol namenode, Tracer tracer) {
     super("");
     this.namenode = namenode;
-    this.traceSampler = traceSampler;
+    this.tracer = tracer;
   }
 
   @Override
   public BatchedEntries<CachePoolEntry> makeRequest(String prevKey)
       throws IOException {
-    TraceScope scope = Trace.startSpan("listCachePools", traceSampler);
+    TraceScope scope = tracer.newScope("listCachePools");
     try {
       return namenode.listCachePools(prevKey);
     } finally {

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/EncryptionZoneIterator.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/EncryptionZoneIterator.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/EncryptionZoneIterator.java
index 0141215..a3cff82 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/EncryptionZoneIterator.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/EncryptionZoneIterator.java
@@ -23,9 +23,8 @@ import java.io.IOException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.BatchedRemoteIterator;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 /**
  * EncryptionZoneIterator is a remote iterator that iterates over encryption
@@ -37,19 +36,18 @@ public class EncryptionZoneIterator
     extends BatchedRemoteIterator<Long, EncryptionZone> {
 
   private final ClientProtocol namenode;
-  private final Sampler<?> traceSampler;
+  private final Tracer tracer;
 
-  public EncryptionZoneIterator(ClientProtocol namenode,
-                                Sampler<?> traceSampler) {
+  public EncryptionZoneIterator(ClientProtocol namenode, Tracer tracer) {
     super(Long.valueOf(0));
     this.namenode = namenode;
-    this.traceSampler = traceSampler;
+    this.tracer = tracer;
   }
 
   @Override
   public BatchedEntries<EncryptionZone> makeRequest(Long prevId)
       throws IOException {
-    TraceScope scope = Trace.startSpan("listEncryptionZones", traceSampler);
+    TraceScope scope = tracer.newScope("listEncryptionZones");
     try {
       return namenode.listEncryptionZones(prevId);
     } finally {

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtoUtil.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtoUtil.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtoUtil.java
index e2e5f39..e585328 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtoUtil.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtoUtil.java
@@ -35,10 +35,8 @@ import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
-import org.apache.htrace.Span;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceInfo;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.SpanId;
+import org.apache.htrace.core.Tracer;
 
 /**
  * Static utilities for dealing with the protocol buffers used by the
@@ -89,39 +87,21 @@ public abstract class DataTransferProtoUtil {
     BaseHeaderProto.Builder builder =  BaseHeaderProto.newBuilder()
       .setBlock(PBHelperClient.convert(blk))
       .setToken(PBHelperClient.convert(blockToken));
-    if (Trace.isTracing()) {
-      Span s = Trace.currentSpan();
+    SpanId spanId = Tracer.getCurrentSpanId();
+    if (spanId.isValid()) {
       builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder()
-          .setTraceId(s.getTraceId())
-          .setParentId(s.getSpanId()));
+          .setTraceId(spanId.getHigh())
+          .setParentId(spanId.getLow()));
     }
     return builder.build();
   }
 
-  public static TraceInfo fromProto(DataTransferTraceInfoProto proto) {
-    if (proto == null) return null;
-    if (!proto.hasTraceId()) return null;
-    return new TraceInfo(proto.getTraceId(), proto.getParentId());
-  }
-
-  public static TraceScope continueTraceSpan(ClientOperationHeaderProto header,
-      String description) {
-    return continueTraceSpan(header.getBaseHeader(), description);
-  }
-
-  public static TraceScope continueTraceSpan(BaseHeaderProto header,
-      String description) {
-    return continueTraceSpan(header.getTraceInfo(), description);
-  }
-
-  public static TraceScope continueTraceSpan(DataTransferTraceInfoProto proto,
-      String description) {
-    TraceScope scope = null;
-    TraceInfo info = fromProto(proto);
-    if (info != null) {
-      scope = Trace.startSpan(description, info);
+  public static SpanId fromProto(DataTransferTraceInfoProto proto) {
+    if ((proto != null) && proto.hasTraceId() &&
+          proto.hasParentId()) {
+      return new SpanId(proto.getTraceId(), proto.getParentId());
     }
-    return scope;
+    return null;
   }
 
   public static void checkBlockOpStatus(

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Sender.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Sender.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Sender.java
index 2d11dc2..e856211 100644
--- a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Sender.java
+++ b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Sender.java
@@ -48,8 +48,8 @@ import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitShm.SlotId;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
 
-import org.apache.htrace.Trace;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.SpanId;
+import org.apache.htrace.core.Tracer;
 
 import com.google.protobuf.Message;
 
@@ -200,10 +200,11 @@ public class Sender implements DataTransferProtocol {
     ReleaseShortCircuitAccessRequestProto.Builder builder =
         ReleaseShortCircuitAccessRequestProto.newBuilder().
         setSlotId(PBHelperClient.convert(slotId));
-    if (Trace.isTracing()) {
-      Span s = Trace.currentSpan();
-      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder()
-          .setTraceId(s.getTraceId()).setParentId(s.getSpanId()));
+    SpanId spanId = Tracer.getCurrentSpanId();
+    if (spanId.isValid()) {
+      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder().
+          setTraceId(spanId.getHigh()).
+          setParentId(spanId.getLow()));
     }
     ReleaseShortCircuitAccessRequestProto proto = builder.build();
     send(out, Op.RELEASE_SHORT_CIRCUIT_FDS, proto);
@@ -214,10 +215,11 @@ public class Sender implements DataTransferProtocol {
     ShortCircuitShmRequestProto.Builder builder =
         ShortCircuitShmRequestProto.newBuilder().
         setClientName(clientName);
-    if (Trace.isTracing()) {
-      Span s = Trace.currentSpan();
-      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder()
-          .setTraceId(s.getTraceId()).setParentId(s.getSpanId()));
+    SpanId spanId = Tracer.getCurrentSpanId();
+    if (spanId.isValid()) {
+      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder().
+          setTraceId(spanId.getHigh()).
+          setParentId(spanId.getLow()));
     }
     ShortCircuitShmRequestProto proto = builder.build();
     send(out, Op.REQUEST_SHORT_CIRCUIT_SHM, proto);

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 9f44e77..2f274a2 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -638,6 +638,8 @@ Release 2.8.0 - UNRELEASED
     HDFS-8740. Move DistributedFileSystem to hadoop-hdfs-client. (Mingliang Liu
     via wheat9)
 
+    HDFS-9080. Update htrace version to 4.0.1 (cmccabe)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs/pom.xml
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/pom.xml b/hadoop-hdfs-project/hadoop-hdfs/pom.xml
index 4c2ded5..0ca878c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/pom.xml
+++ b/hadoop-hdfs-project/hadoop-hdfs/pom.xml
@@ -192,7 +192,7 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
     </dependency>
     <dependency>
       <groupId>org.apache.htrace</groupId>
-      <artifactId>htrace-core</artifactId>
+      <artifactId>htrace-core4</artifactId>
     </dependency>
     <dependency>
       <groupId>org.apache.hadoop</groupId>

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
index 0ba174f..416b9e4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
@@ -64,12 +64,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final String DFS_WEBHDFS_ACL_PERMISSION_PATTERN_DEFAULT =
       HdfsClientConfigKeys.DFS_WEBHDFS_ACL_PERMISSION_PATTERN_DEFAULT;
 
-  // HDFS HTrace configuration is controlled by dfs.htrace.spanreceiver.classes,
-  // etc.
-  public static final String  DFS_SERVER_HTRACE_PREFIX = "dfs.htrace.";
-  @Deprecated
-  public static final String  DFS_CLIENT_HTRACE_PREFIX =
-      HdfsClientConfigKeys.DFS_CLIENT_HTRACE_PREFIX;
+  public static final String DFS_CLIENT_HTRACE_SAMPLER_CLASSES =
+      "dfs.client.htrace.sampler.classes";
 
   // HA related configuration
   public static final String  DFS_DATANODE_RESTART_REPLICA_EXPIRY_KEY = "dfs.datanode.restart.replica.expiration";

http://git-wip-us.apache.org/repos/asf/hadoop/blob/3b9d3262/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Receiver.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Receiver.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Receiver.java
index 59cf884..e040157 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Receiver.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Receiver.java
@@ -18,7 +18,6 @@
 package org.apache.hadoop.hdfs.protocol.datatransfer;
 
 import static org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtoUtil.fromProto;
-import static org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtoUtil.continueTraceSpan;
 import static org.apache.hadoop.hdfs.protocolPB.PBHelperClient.vintPrefixed;
 
 import java.io.DataInputStream;
@@ -27,7 +26,10 @@ import java.io.IOException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
+import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.BaseHeaderProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.CachingStrategyProto;
+import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.ClientOperationHeaderProto;
+import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.DataTransferTraceInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.OpBlockChecksumProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.OpCopyBlockProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.OpReadBlockProto;
@@ -40,14 +42,21 @@ import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.ShortCircuitShmR
 import org.apache.hadoop.hdfs.protocolPB.PBHelperClient;
 import org.apache.hadoop.hdfs.server.datanode.CachingStrategy;
 import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitShm.SlotId;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.SpanId;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 /** Receiver */
 @InterfaceAudience.Private
 @InterfaceStability.Evolving
 public abstract class Receiver implements DataTransferProtocol {
+  private final Tracer tracer;
   protected DataInputStream in;
-  
+
+  protected Receiver(Tracer tracer) {
+    this.tracer = tracer;
+  }
+
   /** Initialize a receiver for DataTransferProtocol with a socket. */
   protected void initialize(final DataInputStream in) {
     this.in = in;
@@ -64,6 +73,26 @@ public abstract class Receiver implements DataTransferProtocol {
     return Op.read(in);
   }
 
+  private TraceScope continueTraceSpan(DataTransferTraceInfoProto proto,
+                                       String description) {
+    TraceScope scope = null;
+    SpanId spanId = fromProto(proto);
+    if (spanId != null) {
+      scope = tracer.newScope(description, spanId);
+    }
+    return scope;
+  }
+
+  private TraceScope continueTraceSpan(ClientOperationHeaderProto header,
+                                             String description) {
+    return continueTraceSpan(header.getBaseHeader(), description);
+  }
+
+  private TraceScope continueTraceSpan(BaseHeaderProto header,
+                                             String description) {
+    return continueTraceSpan(header.getTraceInfo(), description);
+  }
+
   /** Process op by the corresponding method. */
   protected final void processOp(Op op) throws IOException {
     switch(op) {


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