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From "Stephen Yuan Jiang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-17238) Wrong in-memory hbase:meta location causing SSH failure
Date Fri, 02 Dec 2016 08:22:58 GMT
Stephen Yuan Jiang created HBASE-17238:
------------------------------------------

             Summary: Wrong in-memory hbase:meta location causing SSH failure
                 Key: HBASE-17238
                 URL: https://issues.apache.org/jira/browse/HBASE-17238
             Project: HBase
          Issue Type: Bug
          Components: Region Assignment
    Affects Versions: 1.1.0
            Reporter: Stephen Yuan Jiang
            Assignee: Stephen Yuan Jiang
            Priority: Critical


In HBase 1.x, if HMaster#assignMeta() assigns a non-DEFAULT_REPLICA_ID hbase:meta region,
it would wrongly update the DEFAULT_REPLICA_ID hbase:meta region in-memory.  This caused the
in-memory region state has wrong RS information for default replica hbase:meta region.  One
of the problem we saw is a wrong type of SSH could be chosen and causing problems.

{code}
void assignMeta(MonitoredTask status, Set<ServerName> previouslyFailedMetaRSs, int replicaId)
      throws InterruptedException, IOException, KeeperException {
    // Work on meta region
    ...
    if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) {
      status.setStatus("Assigning hbase:meta region");
    } else {
      status.setStatus("Assigning hbase:meta region, replicaId " + replicaId);
    }
    // Get current meta state from zk.
    RegionStates regionStates = assignmentManager.getRegionStates();
    RegionState metaState = MetaTableLocator.getMetaRegionState(getZooKeeper(), replicaId);
    HRegionInfo hri = RegionReplicaUtil.getRegionInfoForReplica(HRegionInfo.FIRST_META_REGIONINFO,
        replicaId);
    ServerName currentMetaServer = metaState.getServerName();
    ...
    boolean rit = this.assignmentManager.
      processRegionInTransitionAndBlockUntilAssigned(hri);
    boolean metaRegionLocation = metaTableLocator.verifyMetaRegionLocation(
      this.getConnection(), this.getZooKeeper(), timeout, replicaId);
    ...
        } else {
      // Region already assigned. We didn't assign it. Add to in-memory state.
      regionStates.updateRegionState(
        HRegionInfo.FIRST_META_REGIONINFO, State.OPEN, currentMetaServer); <<--- Wrong
region to update -->>
      this.assignmentManager.regionOnline(
        HRegionInfo.FIRST_META_REGIONINFO, currentMetaServer); <<--- Wrong region to
update -->>
    }
    ...
{code}

Here is the problem scenario:
Step 1: master failovers (or starts could have the same issue) and find default replica of
hbase:meta is in rs1.
{noformat}
2016-11-26 00:06:36,590 INFO org.apache.hadoop.hbase.master.ServerManager: AssignmentManager
hasn't finished failover cleanup; waiting
2016-11-26 00:06:36,591 INFO org.apache.hadoop.hbase.master.HMaster: hbase:meta with replicaId
0 assigned=0, rit=false, location=rs1,60200,1480103147220
{noformat}
Step 2: master finds that replica 1 of hbase:meta is unassigned, therefore, HMaster#assignMeta()
is called and assign the replica 1 region to rs2, but at the end, it wrongly updates the in-memory
state of default replica to rs2

{noformat}
2016-11-26 00:08:21,741 DEBUG org.apache.hadoop.hbase.master.RegionStates: Onlined 1588230740
on rs2,60200,1480102993815 {ENCODED => 1588230740, NAME => 'hbase:meta,,1', STARTKEY
=> '', ENDKEY => ''}
2016-11-26 00:08:21,741 INFO org.apache.hadoop.hbase.master.RegionStates: Offlined 1588230740
from rs1,60200,1480103147220
2016-11-26 00:08:21,741 INFO org.apache.hadoop.hbase.master.HMaster: hbase:meta with replicaId
1 assigned=0, rit=false, location=rs2,60200,1480102993815
{noformat}

Step 3: now rs1 is down, master needs to choose which SSH to call (MetaServerShutdownHandler
or normal ServerShutdownHandler) - in this case, MetaServerShutdownHandler should be chosen;
however, due to wrong in-memory location, normal ServerShutdownHandler was chosen:

{noformat}
2016-11-26 00:08:33,995 INFO org.apache.hadoop.hbase.zookeeper.RegionServerTracker: RegionServer
ephemeral node deleted, processing expiration [rs1,60200,1480103147220]
2016-11-26 00:08:33,998 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: based on AM,
current region=hbase:meta,,1.1588230740 is on server=rs2,60200,1480102993815 server being
checked: rs1,60200,1480103147220
2016-11-26 00:08:34,001 DEBUG org.apache.hadoop.hbase.master.ServerManager: Added=rs1,60200,1480103147220
to dead servers, submitted shutdown handler to be executed meta=false
{noformat}

Step 4: Wrong SSH was chosen. Due to accessing hbase:meta failure, the SSH failed after retries.
 Now the dead server was not processed; regions in that server remains un-usable (We have
a solution that resolve this issue, but is undesirable: restarting master to cleanup the wrong
in-memory state would make this problem go away):

{noformat}
2016-11-26 00:11:46,550 INFO org.apache.hadoop.hbase.master.handler.ServerShutdownHandler:
Received exception accessing hbase:meta during server shutdown of rs1,60200,1480103147220,
retrying hbase:meta read
org.apache.hadoop.hbase.client.RetriesExhaustedException: Failed after attempts=351, exceptions:
Sat Nov 26 00:11:46 EST 2016, null, java.net.SocketTimeoutException: callTimeout=60000, callDuration=68188:
row '' on table 'hbase:meta' at region=hbase:meta,,1.1588230740, hostname=rs1,60200,1480103147220,
seqNum=0

	at org.apache.hadoop.hbase.client.RpcRetryingCallerWithReadReplicas.throwEnrichedException(RpcRetryingCallerWithReadReplicas.java:271)
	at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:203)
	at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas.call(ScannerCallableWithReplicas.java:60)
	at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:200)
	at org.apache.hadoop.hbase.client.ClientScanner.call(ClientScanner.java:320)
	at org.apache.hadoop.hbase.client.ClientScanner.nextScanner(ClientScanner.java:295)
	at org.apache.hadoop.hbase.client.ClientScanner.initializeScannerInConstruction(ClientScanner.java:160)
	at org.apache.hadoop.hbase.client.ClientScanner.<init>(ClientScanner.java:155)
	at org.apache.hadoop.hbase.client.HTable.getScanner(HTable.java:794)
	at org.apache.hadoop.hbase.MetaTableAccessor.fullScan(MetaTableAccessor.java:602)
	at org.apache.hadoop.hbase.MetaTableAccessor.fullScan(MetaTableAccessor.java:156)
	at org.apache.hadoop.hbase.MetaTableAccessor.getServerUserRegions(MetaTableAccessor.java:555)
	at org.apache.hadoop.hbase.master.handler.ServerShutdownHandler.process(ServerShutdownHandler.java:177)
	at org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:129)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.net.SocketTimeoutException: callTimeout=60000, callDuration=68188: row ''
on table 'hbase:meta' at region=hbase:meta,,1.1588230740, hostname=rs1,60200,1480103147220,
seqNum=0
	at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithRetries(RpcRetryingCaller.java:159)
	at org.apache.hadoop.hbase.client.ResultBoundedCompletionService$QueueingFuture.run(ResultBoundedCompletionService.java:65)
	... 3 more
Caused by: java.io.IOException: Call to rs1/123.45.67.890:60200 failed on local exception:
org.apache.hadoop.hbase.ipc.FailedServerException: This server is in the failed servers list:
rs1/123.45.67.890:60200
	at org.apache.hadoop.hbase.ipc.RpcClientImpl.wrapException(RpcClientImpl.java:1261)
	at org.apache.hadoop.hbase.ipc.RpcClientImpl.call(RpcClientImpl.java:1229)
	at org.apache.hadoop.hbase.ipc.AbstractRpcClient.callBlockingMethod(AbstractRpcClient.java:213)
	at org.apache.hadoop.hbase.ipc.AbstractRpcClient$BlockingRpcChannelImplementation.callBlockingMethod(AbstractRpcClient.java:287)
	at org.apache.hadoop.hbase.protobuf.generated.ClientProtos$ClientService$BlockingStub.scan(ClientProtos.java:32651)
	at org.apache.hadoop.hbase.client.ScannerCallable.openScanner(ScannerCallable.java:372)
	at org.apache.hadoop.hbase.client.ScannerCallable.call(ScannerCallable.java:199)
	at org.apache.hadoop.hbase.client.ScannerCallable.call(ScannerCallable.java:62)
	at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithoutRetries(RpcRetryingCaller.java:200)
	at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas$RetryingRPC.call(ScannerCallableWithReplicas.java:356)
	at org.apache.hadoop.hbase.client.ScannerCallableWithReplicas$RetryingRPC.call(ScannerCallableWithReplicas.java:330)
	at org.apache.hadoop.hbase.client.RpcRetryingCaller.callWithRetries(RpcRetryingCaller.java:126)
	... 4 more
Caused by: org.apache.hadoop.hbase.ipc.FailedServerException: This server is in the failed
servers list: rs1/123.45.67.890:60200
	at org.apache.hadoop.hbase.ipc.RpcClientImpl$Connection.setupIOstreams(RpcClientImpl.java:701)
	at org.apache.hadoop.hbase.ipc.RpcClientImpl$Connection.writeRequest(RpcClientImpl.java:887)
	at org.apache.hadoop.hbase.ipc.RpcClientImpl$Connection.tracedWriteRequest(RpcClientImpl.java:856)
	at org.apache.hadoop.hbase.ipc.RpcClientImpl$Connection$CallSender.run(RpcClientImpl.java:266)
{noformat}



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