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https://issues.apache.org/jira/browse/HBASE-6309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13462745#comment-13462745
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nkeywal commented on HBASE-6309:
--------------------------------
I'm was having a look at this. Could we have the log archiving done by the
regionserver instead of the master? This would lower the work done in the event
thread? The only remaining stuff would be the renaming of the region log dir at
the end.
I see one impact: if the same log was processed simultaneously by multiple
region server, this archiving could occur in parallel on two different region
server. Manageable I think...
> [MTTR] Do NN operations outside of the ZK EventThread in SplitLogManager
> ------------------------------------------------------------------------
>
> Key: HBASE-6309
> URL: https://issues.apache.org/jira/browse/HBASE-6309
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 0.92.1, 0.94.0, 0.96.0
> Reporter: Jean-Daniel Cryans
> Priority: Critical
> Fix For: 0.96.0
>
>
> We found this issue during the leap second cataclysm which prompted a
> distributed splitting of all our logs.
> I saw that none of the RS were splitting after some time while the master was
> showing that it wasn't even 30% done. jstack'ing I saw this:
> {noformat}
> "main-EventThread" daemon prio=10 tid=0x00007f6ce46d8800 nid=0x5376 in
> Object.wait() [0x00007f6ce2ecb000]
> java.lang.Thread.State: WAITING (on object monitor)
> at java.lang.Object.wait(Native Method)
> at java.lang.Object.wait(Object.java:485)
> at org.apache.hadoop.ipc.Client.call(Client.java:1093)
> - locked <0x00000005fdd661a0> (a org.apache.hadoop.ipc.Client$Call)
> at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:226)
> at $Proxy9.rename(Unknown Source)
> at sun.reflect.GeneratedMethodAccessor29.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at
> org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:82)
> at
> org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:59)
> at $Proxy9.rename(Unknown Source)
> at org.apache.hadoop.hdfs.DFSClient.rename(DFSClient.java:759)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem.rename(DistributedFileSystem.java:253)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.moveRecoveredEditsFromTemp(HLogSplitter.java:553)
> at
> org.apache.hadoop.hbase.regionserver.wal.HLogSplitter.moveRecoveredEditsFromTemp(HLogSplitter.java:519)
> at
> org.apache.hadoop.hbase.master.SplitLogManager$1.finish(SplitLogManager.java:138)
> at
> org.apache.hadoop.hbase.master.SplitLogManager.getDataSetWatchSuccess(SplitLogManager.java:431)
> at
> org.apache.hadoop.hbase.master.SplitLogManager.access$1200(SplitLogManager.java:95)
> at
> org.apache.hadoop.hbase.master.SplitLogManager$GetDataAsyncCallback.processResult(SplitLogManager.java:1011)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:571)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:497)
> {noformat}
> We are effectively bottlenecking on doing NN operations and whatever else is
> happening in GetDataAsyncCallback. It was so bad that on our 100 offline
> cluster it took a few hours for the master to process all the incoming ZK
> events while the actual splitting took a fraction of that time.
> I'm marking this as critical and against 0.96 but depending on how involved
> the fix is we might want to backport.
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