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https://issues.apache.org/jira/browse/ACCUMULO-3336?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Josh Elser resolved ACCUMULO-3336.
----------------------------------
Resolution: Cannot Reproduce
Fix Version/s: (was: 1.8.1)
This issue is getting far too much traction from users who think that this is a
bug.
The issue I reported here is not a simple SESSION_EXPIRED from ZooKeeper.
Unless you really understand what's going on, you need to tune the
configuration of Accumulo, HDFS or the Operation System. This is not a "bug".
> ZK session reconnect still results in loss of ZK lock
> -----------------------------------------------------
>
> Key: ACCUMULO-3336
> URL: https://issues.apache.org/jira/browse/ACCUMULO-3336
> Project: Accumulo
> Issue Type: Bug
> Components: zookeeper
> Affects Versions: 1.5.2, 1.6.1
> Reporter: Josh Elser
>
> Saw the following
> {noformat}
> 2014-11-14 08:38:30,612 [zookeeper.DistributedWorkQueue] INFO : Got
> unexpected zookeeper event: None for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/bulk_failed_copyq
> 2014-11-14 08:38:30,621 [zookeeper.ZooCache] WARN : Saw (possibly) transient
> exception communicating with ZooKeeper, will retry
> org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode
> = ConnectionLoss for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/config/tserver.compaction.warn.time
> at org.apache.zookeeper.KeeperException.create(KeeperException.java:99)
> at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
> at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:1045)
> at org.apache.accumulo.fate.zookeeper.ZooCache$2.run(ZooCache.java:260)
> at org.apache.accumulo.fate.zookeeper.ZooCache.retry(ZooCache.java:157)
> at org.apache.accumulo.fate.zookeeper.ZooCache.get(ZooCache.java:285)
> at org.apache.accumulo.fate.zookeeper.ZooCache.get(ZooCache.java:232)
> at
> org.apache.accumulo.server.conf.ZooConfiguration.get(ZooConfiguration.java:96)
> at
> org.apache.accumulo.server.conf.ZooConfiguration._get(ZooConfiguration.java:65)
> at
> org.apache.accumulo.server.conf.ZooConfiguration.get(ZooConfiguration.java:90)
> at
> org.apache.accumulo.core.conf.AccumuloConfiguration.getTimeInMillis(AccumuloConfiguration.java:136)
> at
> org.apache.accumulo.tserver.CompactionWatcher.run(CompactionWatcher.java:84)
> at
> org.apache.accumulo.server.util.time.SimpleTimer$LoggingTimerTask.run(SimpleTimer.java:42)
> at java.util.TimerThread.mainLoop(Timer.java:555)
> at java.util.TimerThread.run(Timer.java:505)
> 2014-11-14 08:38:30,672 [zookeeper.DistributedWorkQueue] INFO : Got
> unexpected zookeeper event: None for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/recovery
> 2014-11-14 08:38:30,672 [zookeeper.ZooLock] DEBUG: event null None
> Disconnected
> 2014-11-14 08:38:31,484 [zookeeper.ZooReader] WARN : Saw (possibly) transient
> exception communicating with ZooKeeper
> org.apache.zookeeper.KeeperException$SessionExpiredException: KeeperErrorCode
> = Session expired for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/tservers/ip-172-31-13-177:37709
> at org.apache.zookeeper.KeeperException.create(KeeperException.java:127)
> at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
> at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:1045)
> at
> org.apache.accumulo.fate.zookeeper.ZooReader.getStatus(ZooReader.java:109)
> at org.apache.accumulo.fate.zookeeper.ZooLock.process(ZooLock.java:381)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:522)
> at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:498)
> 2014-11-14 08:38:31,484 [zookeeper.ZooCache] WARN : Saw (possibly) transient
> exception communicating with ZooKeeper, will retry
> org.apache.zookeeper.KeeperException$SessionExpiredException: KeeperErrorCode
> = Session expired for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/tables/!0/namespace
> at org.apache.zookeeper.KeeperException.create(KeeperException.java:127)
> at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
> at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:1045)
> at org.apache.accumulo.fate.zookeeper.ZooCache$2.run(ZooCache.java:260)
> at org.apache.accumulo.fate.zookeeper.ZooCache.retry(ZooCache.java:157)
> at org.apache.accumulo.fate.zookeeper.ZooCache.get(ZooCache.java:285)
> at org.apache.accumulo.fate.zookeeper.ZooCache.get(ZooCache.java:232)
> at
> org.apache.accumulo.core.client.impl.Tables.getNamespaceId(Tables.java:304)
> at
> org.apache.accumulo.server.conf.TableParentConfiguration.getNamespaceId(TableParentConfiguration.java:47)
> at
> org.apache.accumulo.server.conf.NamespaceConfiguration.getPath(NamespaceConfiguration.java:85)
> at
> org.apache.accumulo.server.conf.NamespaceConfiguration.get(NamespaceConfiguration.java:98)
> at
> org.apache.accumulo.server.conf.ZooCachePropertyAccessor.get(ZooCachePropertyAccessor.java:107)
> at
> org.apache.accumulo.server.conf.TableConfiguration.get(TableConfiguration.java:103)
> at
> org.apache.accumulo.core.conf.AccumuloConfiguration.getCount(AccumuloConfiguration.java:193)
> at
> org.apache.accumulo.tserver.TabletServer$MajorCompactor.run(TabletServer.java:2636)
> at
> org.apache.accumulo.core.util.LoggingRunnable.run(LoggingRunnable.java:34)
> at java.lang.Thread.run(Thread.java:745)
> 2014-11-14 08:38:31,484 [zookeeper.Retry] DEBUG: Sleeping for 250ms before
> retrying operation
> 2014-11-14 08:38:31,485 [zookeeper.ZooSession] DEBUG: Removing closed
> ZooKeeper session to localhost:12644
> 2014-11-14 08:38:31,485 [zookeeper.ZooSession] DEBUG: Connecting to
> localhost:12644 with timeout 30000 with auth
> 2014-11-14 08:38:31,588 [zookeeper.ZooSession] DEBUG: Removing closed
> ZooKeeper session to localhost:12644
> 2014-11-14 08:38:31,588 [zookeeper.ZooSession] DEBUG: Connecting to
> localhost:12644 with timeout 30000 with auth
> 2014-11-14 08:38:31,692 [tserver.TabletServer] DEBUG: gc ParNew=0.10(+0.04)
> secs ConcurrentMarkSweep=0.05(+0.00) secs freemem=118,013,904(+6,412,200)
> totalmem=129,761,280
> 2014-11-14 08:38:31,692 [tserver.TabletServer] WARN : GC pause checker not
> called in a timely fashion. Expected every 5.0 seconds but was 43.1 seconds
> since last check
> 2014-11-14 08:38:31,700 [zookeeper.DistributedWorkQueue] DEBUG: Looking for
> work in /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/bulk_failed_copyq
> 2014-11-14 08:38:31,701 [zookeeper.DistributedWorkQueue] DEBUG: Looking for
> work in /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/recovery
> 2014-11-14 08:38:31,715 [tserver.TabletServer] DEBUG: ScanSess tid
> 172.31.13.177:35935 !0 1 entries in 0.03 secs, nbTimes = [24 24 24.00 1]
> 2014-11-14 08:38:31,737 [trace.ZooTraceClient] DEBUG: Scanning trace hosts in
> zookeeper: /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/tracers
> 2014-11-14 08:38:31,737 [trace.ZooTraceClient] DEBUG: Trace hosts: []
> 2014-11-14 08:38:31,739 [zookeeper.DistributedWorkQueue] INFO : Got
> unexpected zookeeper event: None for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/replication/workqueue
> 2014-11-14 08:38:31,739 [zookeeper.DistributedWorkQueue] INFO : Got
> unexpected zookeeper event: None for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/bulk_failed_copyq
> 2014-11-14 08:38:31,739 [zookeeper.DistributedWorkQueue] INFO : Got
> unexpected zookeeper event: None for
> /accumulo/00f38e67-3c29-4cf0-a394-f423a0b33b6b/recovery
> 2014-11-14 08:38:31,739 [zookeeper.ZooSession] DEBUG: Session expired, state
> of current session : Expired
> 2014-11-14 08:38:31,739 [zookeeper.ZooLock] DEBUG: event null None Expired
> 2014-11-14 08:38:31,741 [tserver.TabletServer] FATAL: Lost tablet server lock
> (reason = SESSION_EXPIRED), exiting.
> {noformat}
> ZooKeeper code appears to had disconnected, closed the disconnected
> connection and then opened a new session. However, the ZooLock, IIRC, didn't
> reconnect and hung the tserver.
> If we want to support this, it might require rehashing some of the ZooLock
> code (to prevent the tserver from processing while the tserver doesn't have
> its lock).
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