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https://issues.apache.org/jira/browse/HBASE-6299?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13411273#comment-13411273
]
Maryann Xue commented on HBASE-6299:
------------------------------------
Currently we don't check concurrent "double" assignment, while it can happen
quite easily after HBASE-5396.
{code}
RegionState state = addToRegionsInTransition(region,
hijack);
synchronized (state) {
assign(region, state, setOfflineInZK, forceNewPlan, hijack);
}
{code}
We now set RegionState OFFLINE in addToRegionsInTransition(), and set ZK node
OFFLINE after we get into the critical section. Why don't we set these two
OFFLINE together in addToRegionsInTransition() and after getting into the
critical section check if RegionState is OFFLINE?
And with "double" assignment, we go directly with assignment() without checking
its current RegionState in addToRegionsInTransition() with calls
forceRegionStateToOffline(). and forceRegionStateToOffline() simply "force" a
RegionState Offline.
{code}
RegionState state = this.regionsInTransition.get(encodedName);
if (state == null) {
state = new RegionState(region, RegionState.State.OFFLINE);
this.regionsInTransition.put(encodedName, state);
} else {
// If we are reassigning the node do not force in-memory state to
OFFLINE.
// Based on the znode state we will decide if to change in-memory state
to
// OFFLINE or not. It will be done before setting znode to OFFLINE
state.
// We often get here with state == CLOSED because ClosedRegionHandler
will
// assign on its tail as part of the handling of a region close.
if (!hijack) {
LOG.debug("Forcing OFFLINE; was=" + state);
state.update(RegionState.State.OFFLINE);
}
}
{code}
With this piece of code, we normally see logs like "Forcing OFFLINE;
was=regionName state=CLOSED" with load balance. but in "double" assignment, we
can see "Forcing OFFLINE; was=regionName state=OPEN". Should we ensure the
state is CLOSED or OFFLINE before proceeding to assignment?
> RS starts region open while fails ack to HMaster.sendRegionOpen() causes
> inconsistency in HMaster's region state and a series of successive problems.
> -----------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-6299
> URL: https://issues.apache.org/jira/browse/HBASE-6299
> Project: HBase
> Issue Type: Bug
> Components: master
> Affects Versions: 0.90.6, 0.94.0
> Reporter: Maryann Xue
> Assignee: Maryann Xue
> Priority: Critical
> Attachments: HBASE-6299-v2.patch, HBASE-6299.patch
>
>
> 1. HMaster tries to assign a region to an RS.
> 2. HMaster creates a RegionState for this region and puts it into
> regionsInTransition.
> 3. In the first assign attempt, HMaster calls RS.openRegion(). The RS
> receives the open region request and starts to proceed, with success
> eventually. However, due to network problems, HMaster fails to receive the
> response for the openRegion() call, and the call times out.
> 4. HMaster attemps to assign for a second time, choosing another RS.
> 5. But since the HMaster's OpenedRegionHandler has been triggered by the
> region open of the previous RS, and the RegionState has already been removed
> from regionsInTransition, HMaster finds invalid and ignores the unassigned ZK
> node "RS_ZK_REGION_OPENING" updated by the second attempt.
> 6. The unassigned ZK node stays and a later unassign fails coz
> RS_ZK_REGION_CLOSING cannot be created.
> {code}
> 2012-06-29 07:03:38,870 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Using pre-existing plan for
> region
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.;
>
> plan=hri=CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.,
> src=swbss-hadoop-004,60020,1340890123243,
> dest=swbss-hadoop-006,60020,1340890678078
> 2012-06-29 07:03:38,870 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Assigning region
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> to swbss-hadoop-006,60020,1340890678078
> 2012-06-29 07:03:38,870 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=M_ZK_REGION_OFFLINE, server=swbss-hadoop-002:60000,
> region=b713fd655fa02395496c5a6e39ddf568
> 2012-06-29 07:06:28,882 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_OPENING, server=swbss-hadoop-006,60020,1340890678078,
> region=b713fd655fa02395496c5a6e39ddf568
> 2012-06-29 07:06:32,291 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_OPENING, server=swbss-hadoop-006,60020,1340890678078,
> region=b713fd655fa02395496c5a6e39ddf568
> 2012-06-29 07:06:32,299 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_OPENED, server=swbss-hadoop-006,60020,1340890678078,
> region=b713fd655fa02395496c5a6e39ddf568
> 2012-06-29 07:06:32,299 DEBUG
> org.apache.hadoop.hbase.master.handler.OpenedRegionHandler: Handling OPENED
> event for
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> from serverName=swbss-hadoop-006,60020,1340890678078, load=(requests=518945,
> regions=575, usedHeap=15282, maxHeap=31301); deleting unassigned node
> 2012-06-29 07:06:32,299 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> master:60000-0x2377fee2ae80007 Deleting existing unassigned node for
> b713fd655fa02395496c5a6e39ddf568 that is in expected state RS_ZK_REGION_OPENED
> 2012-06-29 07:06:32,301 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> master:60000-0x2377fee2ae80007 Successfully deleted unassigned node for
> region b713fd655fa02395496c5a6e39ddf568 in expected state RS_ZK_REGION_OPENED
> 2012-06-29 07:06:32,301 DEBUG
> org.apache.hadoop.hbase.master.handler.OpenedRegionHandler: The master has
> opened the region
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> that was online on serverName=swbss-hadoop-006,60020,1340890678078,
> load=(requests=518945, regions=575, usedHeap=15282, maxHeap=31301)
> 2012-06-29 07:07:41,140 WARN
> org.apache.hadoop.hbase.master.AssignmentManager: Failed assignment of
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> to serverName=swbss-hadoop-006,60020,1340890678078, load=(requests=0,
> regions=575, usedHeap=0, maxHeap=0), trying to assign elsewhere instead;
> retry=0
> java.net.SocketTimeoutException: Call to /172.16.0.6:60020 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=/172.16.0.2:53765
> remote=/172.16.0.6:60020]
> 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 $Proxy8.openRegion(Unknown Source)
> at
> org.apache.hadoop.hbase.master.ServerManager.sendRegionOpen(ServerManager.java:573)
> at
> org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:1127)
> at
> org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:912)
> at
> org.apache.hadoop.hbase.master.AssignmentManager.assign(AssignmentManager.java:892)
> at
> org.apache.hadoop.hbase.master.handler.ClosedRegionHandler.process(ClosedRegionHandler.java:92)
> at
> org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:162)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
> Caused by: java.net.SocketTimeoutException: 120000 millis timeout while
> waiting for channel to be ready for read. ch :
> java.nio.channels.SocketChannel[connected local=/172.16.0.2:53765
> remote=/172.16.0.6:60020]
> at
> org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:164)
> at
> org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
> at
> org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
> at java.io.FilterInputStream.read(FilterInputStream.java:116)
> at
> org.apache.hadoop.hbase.ipc.HBaseClient$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)
> 2012-06-29 07:07:41,142 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: No previous transition plan
> was found (or we are ignoring an existing plan) for
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> so generated a random one;
> hri=CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.,
> src=, dest=swbss-hadoop-164,60020,1340888346294; 15 (online=15,
> exclude=serverName=swbss-hadoop-006,60020,1340890678078, load=(requests=0,
> regions=575, usedHeap=0, maxHeap=0)) available servers
> 2012-06-29 07:07:41,142 DEBUG org.apache.hadoop.hbase.zookeeper.ZKAssign:
> master:60000-0x2377fee2ae80007 Creating (or updating) unassigned node for
> b713fd655fa02395496c5a6e39ddf568 with OFFLINE state
> 2012-06-29 07:07:41,145 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Using pre-existing plan for
> region
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.;
>
> plan=hri=CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.,
> src=, dest=swbss-hadoop-164,60020,1340888346294
> 2012-06-29 07:07:41,145 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Assigning region
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> to swbss-hadoop-164,60020,1340888346294
> 2012-06-29 07:07:41,149 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_OPENING, server=swbss-hadoop-164,60020,1340888346294,
> region=b713fd655fa02395496c5a6e39ddf568
> 2012-06-29 07:07:41,150 WARN
> org.apache.hadoop.hbase.master.AssignmentManager: Received OPENING for region
> b713fd655fa02395496c5a6e39ddf568 from server
> swbss-hadoop-164,60020,1340888346294 but region was in the state null and
> not in expected PENDING_OPEN or OPENING states
> 2012-06-29 07:07:41,296 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_OPENING, server=swbss-hadoop-164,60020,1340888346294,
> region=b713fd655fa02395496c5a6e39ddf568
> 2012-06-29 07:07:41,296 WARN
> org.apache.hadoop.hbase.master.AssignmentManager: Received OPENING for region
> b713fd655fa02395496c5a6e39ddf568 from server
> swbss-hadoop-164,60020,1340888346294 but region was in the state null and
> not in expected PENDING_OPEN or OPENING states
> 2012-06-29 07:07:41,302 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Handling
> transition=RS_ZK_REGION_OPENED, server=swbss-hadoop-164,60020,1340888346294,
> region=b713fd655fa02395496c5a6e39ddf568
> 2012-06-29 07:07:41,302 WARN
> org.apache.hadoop.hbase.master.AssignmentManager: Received OPENED for region
> b713fd655fa02395496c5a6e39ddf568 from server
> swbss-hadoop-164,60020,1340888346294 but region was in the state null and
> not in expected PENDING_OPEN or OPENING states
> 2012-06-29 07:08:38,872 INFO org.apache.hadoop.hbase.master.HMaster: balance
> hri=CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.,
> src=swbss-hadoop-006,60020,1340890678078,
> dest=swbss-hadoop-008,60020,1340891085175
> 2012-06-29 07:08:38,872 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Starting unassignment of
> region
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> (offlining)
> 2012-06-29 07:08:47,875 DEBUG
> org.apache.hadoop.hbase.master.AssignmentManager: Sent CLOSE to
> serverName=swbss-hadoop-006,60020,1340890678078, load=(requests=0, regions=0,
> usedHeap=0, maxHeap=0) for region
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> ...
> 2012-06-29 08:04:37,681 INFO
> org.apache.hadoop.hbase.master.AssignmentManager: Regions in transition timed
> out:
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> state=PENDING_CLOSE, ts=1340926468331, server=null
> 2012-06-29 08:04:37,681 INFO
> org.apache.hadoop.hbase.master.AssignmentManager: Region has been
> PENDING_CLOSE for too long, running forced unassign again on
> region=CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> 2012-06-29 08:04:47,681 INFO
> org.apache.hadoop.hbase.master.AssignmentManager: Regions in transition timed
> out:
> CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> state=PENDING_CLOSE, ts=1340926468331, server=null
> 2012-06-29 08:04:47,682 INFO
> org.apache.hadoop.hbase.master.AssignmentManager: Region has been
> PENDING_CLOSE for too long, running forced unassign again on
> region=CDR_STATS_TRAFFIC,13184390567|20120508|17||2|3|913,1337256975556.b713fd655fa02395496c5a6e39ddf568.
> {code}
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