You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@hbase.apache.org by "Tomu Tsuruhara (JIRA)" <ji...@apache.org> on 2016/09/12 13:43:20 UTC
[jira] [Created] (HBASE-16616) Rpc handlers stuck on
ThreadLocalMap.expungeStaleEntry
Tomu Tsuruhara created HBASE-16616:
--------------------------------------
Summary: Rpc handlers stuck on ThreadLocalMap.expungeStaleEntry
Key: HBASE-16616
URL: https://issues.apache.org/jira/browse/HBASE-16616
Project: HBase
Issue Type: Improvement
Components: Performance
Affects Versions: 1.2.2
Reporter: Tomu Tsuruhara
In our HBase 1.2.2 cluster, some regionserver showed too bad "QueueCallTime_99th_percentile" exceeding 10 seconds.
Most rpc handler threads stuck on ThreadLocalMap.expungeStaleEntry call at that time.
{noformat}
"PriorityRpcServer.handler=18,queue=0,port=16020" #322 daemon prio=5 os_prio=0 tid=0x00007fd422062800 nid=0x19b89 runnable [0x00007fcb8a821000]
java.lang.Thread.State: RUNNABLE
at java.lang.ThreadLocal$ThreadLocalMap.expungeStaleEntry(ThreadLocal.java:617)
at java.lang.ThreadLocal$ThreadLocalMap.remove(ThreadLocal.java:499)
at java.lang.ThreadLocal$ThreadLocalMap.access$200(ThreadLocal.java:298)
at java.lang.ThreadLocal.remove(ThreadLocal.java:222)
at java.util.concurrent.locks.ReentrantReadWriteLock$Sync.tryReleaseShared(ReentrantReadWriteLock.java:426)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.releaseShared(AbstractQueuedSynchronizer.java:1341)
at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.unlock(ReentrantReadWriteLock.java:881)
at com.yammer.metrics.stats.ExponentiallyDecayingSample.unlockForRegularUsage(ExponentiallyDecayingSample.java:196)
at com.yammer.metrics.stats.ExponentiallyDecayingSample.update(ExponentiallyDecayingSample.java:113)
at com.yammer.metrics.stats.ExponentiallyDecayingSample.update(ExponentiallyDecayingSample.java:81)
at org.apache.hadoop.metrics2.lib.MutableHistogram.add(MutableHistogram.java:81)
at org.apache.hadoop.metrics2.lib.MutableRangeHistogram.add(MutableRangeHistogram.java:59)
at org.apache.hadoop.hbase.ipc.MetricsHBaseServerSourceImpl.dequeuedCall(MetricsHBaseServerSourceImpl.java:194)
at org.apache.hadoop.hbase.ipc.MetricsHBaseServer.dequeuedCall(MetricsHBaseServer.java:76)
at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2192)
at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:112)
at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:133)
at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:108)
at java.lang.Thread.run(Thread.java:745)
{noformat}
We were using jdk 1.8.0_92 and here is a snippet from ThreadLocal.java.
{code}
616: while (tab[h] != null)
617: h = nextIndex(h, len);
{code}
So I hypothesized that there're too many consecutive entries in {{tab}} array and actually I found them in the heapdump.
Most of those entries pointed at instance of {{org.apache.hadoop.hbase.util.Counter$1}}
which is equivarent to {{indexHolderThreadLocal}} instance-variable in the {{Counter}} class.
Because {{RpcServer$Connection}} class creates a {{Counter}} instance {{rpcCount}} for every connections,
it is possible to have lots of {{Counter#indexHolderThreadLocal}} instances in RegionServer process
when we repeat connect-and-close from client. As a result, a ThreadLocalMap can have lots of consecutive
entires.
Usually, since each entry is a {{WeakReference}}, these entries are collected and removed
by garbage-collector soon after connection closed.
But if connection's life-time was long enough to survive youngGC, it wouldn't be collected until old-gen collector runs.
Furthermore, under G1GC deployment, it is possible not to be collected even by old-gen GC(mixed GC)
if entries sit in a region which doesn't have much garbages.
Actually we used G1GC when we encountered this problem.
We should remove the entry from ThreadLocalMap by calling ThreadLocal#remove explicitly.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)