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Date: Thu, 19 Apr 2012 03:33:24 +0000 (UTC)
From: "Maryann Xue (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-5816) Balancer and ServerShutdownHandler
 concurrently reassigning the same region
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    [ https://issues.apache.org/jira/browse/HBASE-5816?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13257195#comment-13257195 ] 

Maryann Xue commented on HBASE-5816:
------------------------------------

stack, your suggestion seems an ultimate solution to the current HMaster workflow. trunk has the same problem.
The case i attached were actually introduced by HBASE-5396, which tried to let ServerShutdownHandler assign the region in an earlier stage instead of waiting for the TimeoutMonitor to do the job. But the isRegionOnline test seems too weak here.
      for (HRegionInfo hri : regionsFromRegionPlansForServer) {
        if (!this.services.getAssignmentManager().isRegionOnline(hri)) {
          this.services.getAssignmentManager().assign(hri, true);
          reassignedPlans++;
        }
      }

However, i think any client call to HBaseAdmin.assign() that coincide at this point would cause the same problem. There is a lock guarding the private assign() method to deal with concurrent assigns, but the entire assign process is not atomic. It should be safe for the later thread just return or get an exception if the region has already been assigned by an earlier thread.
                
> Balancer and ServerShutdownHandler concurrently reassigning the same region
> ---------------------------------------------------------------------------
>
>                 Key: HBASE-5816
>                 URL: https://issues.apache.org/jira/browse/HBASE-5816
>             Project: HBase
>          Issue Type: Bug
>          Components: master
>    Affects Versions: 0.90.6
>            Reporter: Maryann Xue
>            Priority: Critical
>         Attachments: HBASE-5816.patch
>
>
> The first assign thread exits with success after updating the RegionState to PENDING_OPEN, while the second assign follows immediately into "assign" and fails the RegionState check in setOfflineInZooKeeper(). This causes the master to abort.
> In the below case, the two concurrent assigns occurred when AM tried to assign a region to a dying/dead RS, and meanwhile the ShutdownServerHandler tried to assign this region (from the region plan) spontaneously.
> 2012-04-17 05:44:57,648 INFO org.apache.hadoop.hbase.master.HMaster: balance hri=TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b., src=hadoop05.sh.intel.com,60020,1334544902186, dest=xmlqa-clv16.sh.intel.com,60020,1334612497253
> 2012-04-17 05:44:57,648 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Starting unassignment of region TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. (offlining)
> 2012-04-17 05:44:57,648 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Sent CLOSE to serverName=hadoop05.sh.intel.com,60020,1334544902186, load=(requests=0, regions=0, usedHeap=0, maxHeap=0) for region TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b.
> 2012-04-17 05:44:57,666 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Handling new unassigned node: /hbase/unassigned/fe38fe31caf40b6e607a3e6bbed6404b (region=TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b., server=hadoop05.sh.intel.com,60020,1334544902186, state=RS_ZK_REGION_CLOSING)
> 2012-04-17 05:52:58,984 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Forcing OFFLINE; was=TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. state=CLOSED, ts=1334612697672, server=hadoop05.sh.intel.com,60020,1334544902186
> 2012-04-17 05:52:58,984 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign: master:60000-0x236b912e9b3000e Creating (or updating) unassigned node for fe38fe31caf40b6e607a3e6bbed6404b with OFFLINE state
> 2012-04-17 05:52:59,096 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Using pre-existing plan for region TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b.; plan=hri=TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b., src=hadoop05.sh.intel.com,60020,1334544902186, dest=xmlqa-clv16.sh.intel.com,60020,1334612497253
> 2012-04-17 05:52:59,096 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Assigning region TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. to xmlqa-clv16.sh.intel.com,60020,1334612497253
> 2012-04-17 05:54:19,159 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Forcing OFFLINE; was=TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. state=PENDING_OPEN, ts=1334613179096, server=xmlqa-clv16.sh.intel.com,60020,1334612497253
> 2012-04-17 05:54:59,033 WARN org.apache.hadoop.hbase.master.AssignmentManager: Failed assignment of TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. to serverName=xmlqa-clv16.sh.intel.com,60020,1334612497253, load=(requests=0, regions=0, usedHeap=0, maxHeap=0), trying to assign elsewhere instead; retry=0
> java.net.SocketTimeoutException: Call to /10.239.47.87:60020 failed on socket timeout exception: java.net.SocketTimeoutException: 120000 millis timeout while waiting for channel to be ready for read. ch : java.nio.channels.SocketChannel[connected local=/10.239.47.89:41302 remote=/10.239.47.87:60020]
>         at org.apache.hadoop.hbase.ipc.HBaseClient.wrapException(HBaseClient.java:805)
>         at org.apache.hadoop.hbase.ipc.HBaseClient.call(HBaseClient.java:778)
>         at org.apache.hadoop.hbase.ipc.HBaseRPC$Invoker.invoke(HBaseRPC.java:283)
>         at $Proxy7.openRegion(Unknown Source)
>         at org.apache.hadoop.hbase.master.ServerManager.sendRegionOpen(ServerManager.java:573)
>         at org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:1127)
>         at org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:912)
>         at org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:892)
>         at org.apache.hadoop.hbase.master.handler.ClosedRegionHandler.process(ClosedRegionHandler.java:92)
>         at org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:162)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
>         at java.lang.Thread.run(Thread.java:662)
> Caused by: java.net.SocketTimeoutException: 120000 millis timeout while waiting for channel to be ready for read. ch : java.nio.channels.SocketChannel[connected local=/10.239.47.89:41302 remote=/10.239.47.87:60020]
>         at org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:164)
>         at org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
>         at org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
>         at java.io.FilterInputStream.read(FilterInputStream.java:116)
>         at org.apache.hadoop.hbase.ipc.HBaseClient$Connection$PingInputStream.read(HBaseClient.java:301)
>         at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
>         at java.io.BufferedInputStream.read(BufferedInputStream.java:237)
>         at java.io.DataInputStream.readInt(DataInputStream.java:370)
>         at org.apache.hadoop.hbase.ipc.HBaseClient$Connection.receiveResponse(HBaseClient.java:541)
>         at org.apache.hadoop.hbase.ipc.HBaseClient$Connection.run(HBaseClient.java:479)
> 2012-04-17 05:54:59,035 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: No previous transition plan was found (or we are ignoring an existing plan) for TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. so generated a random one; hri=TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b., src=, dest=hadoop06.sh.intel.com,60020,1334544901894; 7 (online=7, exclude=serverName=xmlqa-clv16.sh.intel.com,60020,1334612497253, load=(requests=0, regions=0, usedHeap=0, maxHeap=0)) available servers
> 2012-04-17 05:54:59,035 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign: master:60000-0x236b912e9b3000e Creating (or updating) unassigned node for fe38fe31caf40b6e607a3e6bbed6404b with OFFLINE state
> 2012-04-17 05:54:59,045 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Using pre-existing plan for region TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b.; plan=hri=TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b., src=, dest=hadoop06.sh.intel.com,60020,1334544901894
> 2012-04-17 05:54:59,045 DEBUG org.apache.hadoop.hbase.master.AssignmentManager: Assigning region TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. to hadoop06.sh.intel.com,60020,1334544901894
> 2012-04-17 05:54:59,046 FATAL org.apache.hadoop.hbase.master.HMaster: Unexpected state trying to OFFLINE; TABLE_ORDER_CUSTOMER,,1334017820846.fe38fe31caf40b6e607a3e6bbed6404b. state=PENDING_OPEN, ts=1334613299045, server=hadoop06.sh.intel.com,60020,1334544901894
> java.lang.IllegalStateException
>         at org.apache.hadoop.hbase.master.AssignmentManager.setOfflineInZooKeeper(AssignmentManager.java:1167)
>         at org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:1107)
>         at org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:912)
>         at org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:892)
>         at org.apache.hadoop.hbase.master.handler.ServerShutdownHandler.process(ServerShutdownHandler.java:259)
>         at org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:162)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
>         at java.lang.Thread.run(Thread.java:662)
> 2012-04-17 05:54:59,047 INFO org.apache.hadoop.hbase.master.HMaster: Aborting

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