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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7251) Avoid flood logs during client disconnect during batch get operation
Date Sun, 02 Dec 2012 05:53:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13508171#comment-13508171

Hadoop QA commented on HBASE-7251:

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:red}-1 tests included{color}.  The patch doesn't appear to include any new or modified
                        Please justify why no new tests are needed for this patch.
                        Also please list what manual steps were performed to verify this patch.

    {color:red}-1 patch{color}.  The patch command could not apply the patch.

Console output: https://builds.apache.org/job/PreCommit-HBASE-Build/3429//console

This message is automatically generated.
> Avoid flood logs during client disconnect during batch get operation
> --------------------------------------------------------------------
>                 Key: HBASE-7251
>                 URL: https://issues.apache.org/jira/browse/HBASE-7251
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.94.2
>            Reporter: Fengdong Yu
>              Labels: patch
>             Fix For: 0.94.3
>         Attachments: HBASE-7251.patch
> Background:
> A smart guy in the company want to read data from the HBASE in batch, the code like the
following:(just demonstrate, not runnable):
> 	List<Get> gets = new ArrayList<Get>();
> 	for(int i =0; i < n; ++i){
> 		gets.add("some row key here");
> 		if (i % 10000 == 0){
> 			Results[] results = htable.get(gets);
> 			//process results here.  so delete some code
> 		}
> 	}
> Yes, you know that, this guy forgot "gets.clear()"  after each "htable.get()" operation
in his code.
> One region server becomes very slow, and crashed after 30mins becauseof OOM, but we got
15GB log file.
> there are flood logs as following:
> ERROR org.apache.hadoop.hbase.regionserver.HRegionServer:
> org.apache.hadoop.hbase.ipc.CallerDisconnectedException: Aborting call multi(org.apache.hadoop.hbase.client.MultiAction@49540d8d),
rpc version=1, client version=29, methodsFingerPrint=-56040613 from after 3980
ms, since caller disconnected
>         at org.apache.hadoop.hbase.ipc.HBaseServer$Call.throwExceptionIfCallerDisconnected(HBaseServer.java:436)
>         at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.nextInternal(HRegion.java:3468)
>         at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.next(HRegion.java:3425)
>         at org.apache.hadoop.hbase.regionserver.HRegion$RegionScannerImpl.next(HRegion.java:3449)
>         at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:4198)
>         at org.apache.hadoop.hbase.regionserver.HRegion.get(HRegion.java:4171)
>         at org.apache.hadoop.hbase.regionserver.HRegionServer.get(HRegionServer.java:1993)
>         at org.apache.hadoop.hbase.regionserver.HRegionServer.multi(HRegionServer.java:3410)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.lang.reflect.Method.invoke(Method.java:601)
>         at org.apache.hadoop.hbase.ipc.WritableRpcEngine$Server.call(WritableRpcEngine.java:364)
>         at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1409)
> Fix:
> Server is stop "get" but cannot exit from the "for" loop, so write flood logs here.
> My patch just log one exception log instead of flood logs. 
> Importantly, server stop processing immediately if client timeout or disconnect.
> Test:
> I used this guy's wrong code read data( NO "gets.clear()" ) from the HBASE, when it becomes
very slow to get results, I pressed ctrl+C, then there is only ONE CallerDisconnectedException
exception log and the server stop reading immediately, LOG generate the last log entry:
>  WARN org.apache.hadoop.ipc.HBaseServer: IPC Server handler 1 on 60020 caught a ClosedChannelException,
this means that the server was processing a request but the client went away. The error message
was: null

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