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From li...@apache.org
Subject svn commit: r1505598 - in /hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase: HConstants.java regionserver/MemStore.java
Date Mon, 22 Jul 2013 04:59:31 GMT
Author: liyin
Date: Mon Jul 22 04:59:31 2013
New Revision: 1505598

URL: http://svn.apache.org/r1505598
Log:
[HBASE-3855] Linear reseek fix.

Author: shaneh

Summary:
This fixes the linear reseek by setting a config limit
on how many KVs to search through before falling back to seek.

For details on the issue being address see HBASE-4195, HBASE-3855,
& HBASE-6591.

Test Plan: Bake in shadow

Reviewers: aaiyer, liyintang

Reviewed By: aaiyer

CC: hbase-eng@

Differential Revision: https://phabricator.fb.com/D891527

Task ID: 2491819

Modified:
    hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/HConstants.java
    hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.java

Modified: hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/HConstants.java
URL: http://svn.apache.org/viewvc/hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/HConstants.java?rev=1505598&r1=1505597&r2=1505598&view=diff
==============================================================================
--- hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/HConstants.java (original)
+++ hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/HConstants.java Mon Jul 22
04:59:31 2013
@@ -810,6 +810,13 @@ public final class HConstants {
   public final static float MSLAB_PCT_LOWER_LIMIT = 0.0f;
   public final static float MSLAB_PCT_UPPER_LIMIT = 2.0f;
 
+
+  /*
+   * Memstore Linear search limit
+   */
+  public final static String MEMSTORE_RESEEK_LINEAR_SEARCH_LIMIT_KEY = "hbase.hregion.memstore.linear.search.limit";
+  public final static int MEMSTORE_RESEEK_LINEAR_SEARCH_LIMIT_DEFAULT = 20;
+
   private HConstants() {
     // Can't be instantiated with this constructor.
   }

Modified: hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.java
URL: http://svn.apache.org/viewvc/hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.java?rev=1505598&r1=1505597&r2=1505598&view=diff
==============================================================================
--- hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.java
(original)
+++ hbase/branches/0.89-fb/src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.java
Mon Jul 22 04:59:31 2013
@@ -581,6 +581,10 @@ public class MemStore implements HeapSiz
     volatile MemStoreLAB allocatorAtCreation;
     volatile MemStoreLAB snapshotAllocatorAtCreation;
 
+    // The maximum number of kvs to search linearly before doing a seek
+    private int maxLinearReseeks = conf.getInt(HConstants.MEMSTORE_RESEEK_LINEAR_SEARCH_LIMIT_KEY,
+        HConstants.MEMSTORE_RESEEK_LINEAR_SEARCH_LIMIT_DEFAULT);
+
     /*
     Some notes...
 
@@ -614,13 +618,11 @@ public class MemStore implements HeapSiz
         this.snapshotAllocatorAtCreation.incScannerCount();
       }
 
-      //DebugPrint.println(" MS new@" + hashCode());
     }
 
     protected KeyValue getNext(Iterator<KeyValue> it) {
       KeyValue ret = null;
       long readPoint = MultiVersionConsistencyControl.getThreadReadPoint();
-      //DebugPrint.println( " MS@" + hashCode() + ": threadpoint = " + readPoint);
 
       while (ret == null && it.hasNext()) {
         KeyValue v = it.next();
@@ -649,14 +651,6 @@ public class MemStore implements HeapSiz
       kvsetNextRow = getNext(kvsetIt);
       snapshotNextRow = getNext(snapshotIt);
 
-
-      //long readPoint = MultiVersionConsistencyControl.getThreadReadPoint();
-      //DebugPrint.println( " MS@" + hashCode() + " kvset seek: " + kvsetNextRow + " with
size = " +
-      //    kvset.size() + " threadread = " + readPoint);
-      //DebugPrint.println( " MS@" + hashCode() + " snapshot seek: " + snapshotNextRow +
" with size = " +
-      //    snapshot.size() + " threadread = " + readPoint);
-
-
       KeyValue lowest = getLowest();
 
       // has data := (lowest != null)
@@ -664,13 +658,32 @@ public class MemStore implements HeapSiz
     }
 
     @Override
-    public boolean reseek(KeyValue key) {
-      //shaneh Jul-17-2013: Temporary fix while a more efficient reseek is worked on.
-      return seek(key);
+    public synchronized boolean reseek(KeyValue key) {
+
+      //Limit the number of kvs to search linearly before triggering a seek.
+      int seeked = 0;
+
+      while (kvsetNextRow != null &&
+          comparator.compare(kvsetNextRow, key) < 0 &&
+          seeked++ < this.maxLinearReseeks) {
+        kvsetNextRow = getNext(kvsetIt);
+      }
+
+      while (snapshotNextRow != null &&
+          comparator.compare(snapshotNextRow, key) < 0 &&
+          seeked++ < this.maxLinearReseeks) {
+        snapshotNextRow = getNext(snapshotIt);
+      }
+
+      // The linear reseek took more than the maximum allowed by config.
+      if (seeked >= this.maxLinearReseeks) {
+        return seek(key);
+      }
+
+      return (kvsetNextRow != null || snapshotNextRow != null);
     }
 
     public synchronized KeyValue peek() {
-      //DebugPrint.println(" MS@" + hashCode() + " peek = " + getLowest());
       return getLowest();
     }
 
@@ -689,9 +702,6 @@ public class MemStore implements HeapSiz
         snapshotNextRow = getNext(snapshotIt);
       }
 
-      //long readpoint = MultiVersionConsistencyControl.getThreadReadPoint();
-      //DebugPrint.println(" MS@" + hashCode() + " next: " + theNext + " next_next: " +
-      //    getLowest() + " threadpoint=" + readpoint);
       return theNext;
     }
 



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