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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8698) potential thread creation in MetaScanner.metaScan
Date Thu, 25 Jul 2013 22:47:48 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8698?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13720170#comment-13720170
] 

Hadoop QA commented on HBASE-8698:
----------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12594261/8698-trunk.txt
  against trunk revision .

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

    {color:green}+1 tests included{color}.  The patch appears to include 6 new or modified
tests.

    {color:green}+1 hadoop1.0{color}.  The patch compiles against the hadoop 1.0 profile.

    {color:green}+1 hadoop2.0{color}.  The patch compiles against the hadoop 2.0 profile.

    {color:green}+1 javadoc{color}.  The javadoc tool did not generate any warning messages.

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of
javac compiler warnings.

    {color:green}+1 findbugs{color}.  The patch does not introduce any new Findbugs (version
1.3.9) warnings.

    {color:green}+1 release audit{color}.  The applied patch does not increase the total number
of release audit warnings.

    {color:red}-1 lineLengths{color}.  The patch introduces lines longer than 100

  {color:green}+1 site{color}.  The mvn site goal succeeds with this patch.

    {color:green}+1 core tests{color}.  The patch passed unit tests in .

Test results: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//testReport/
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-protocol.html
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-client.html
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-examples.html
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop1-compat.html
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-prefix-tree.html
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-common.html
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-server.html
Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop-compat.html
Console output: https://builds.apache.org/job/PreCommit-HBASE-Build/6468//console

This message is automatically generated.
                
> potential thread creation in MetaScanner.metaScan
> -------------------------------------------------
>
>                 Key: HBASE-8698
>                 URL: https://issues.apache.org/jira/browse/HBASE-8698
>             Project: HBase
>          Issue Type: Bug
>          Components: Client
>    Affects Versions: 0.94.7
>            Reporter: Kireet Reddy
>            Assignee: Lars Hofhansl
>             Fix For: 0.98.0, 0.95.2, 0.94.11
>
>         Attachments: 8698-trunk.txt
>
>
> MetaScanner.metaScan() creates an instance of HTable per call. The constructur used creates
a new ThreadPoolExecutor. The executor itself will not create a thread unless it's pool is
used. I am not sure if the HTable instance in question ever uses it's pool. But if so, this
could become a big performance issue. Logging an issue at Lars's request. mail list chain
below.
> ------------------------------------- 
> Indeed. That is bad.
> I cannot see a clean fix immediately, but we need to look at this.
> Mind filing a ticket, Kireet?
> -- Lars
> ________________________________
>  From: Kireet <kireet-Teh5dPVPL8nQT0dZR+AlfA@public.gmane.org>
> To: public-user-50Pas4EWwPEyzMRdD/IqWQ-wOFGN7rlS/M9smdsby/KFg@public.gmane.org 
> Sent: Friday, May 31, 2013 11:58 AM
> Subject: Re: HConnectionManager$HConnectionImplementation.locateRegionInMeta
>  
> Even if I initiate the call via a pooled htable, the MetaScanner seems 
> to use a concrete HTable instance. The constructor invoked seems to 
> create a java ThreadPoolExecutor. I am not 100% sure but I think as long 
> as nothing is submitted to the ThreadPoolExecutor it won't create any 
> threads. I just wanted to confirm this was the case. I do see the 
> connection is shared.
> --Kireet
> On 5/30/13 7:38 PM, Ted Yu wrote:
> > HTablePool$**PooledHTable is a wrapper around HTable.
> >
> > Here is how HTable obtains a connection:
> >
> >     public HTable(Configuration conf, final byte[] tableName, final
> > ExecutorService pool)
> >         throws IOException {
> >       this.connection = HConnectionManager.getConnection(conf);
> >
> > Meaning the connection is a shared one based on certain key/value pairs
> > from conf.
> >
> > bq. So every call to batch will create a new thread?
> >
> > I don't think so.
> >
> > On Thu, May 30, 2013 at 11:28 AM, Kireet <kireet-Teh5dPVPL8nQT0dZR+AlfA-XMD5yJDbdMReXY1tMh2IBg@public.gmane.org>
wrote:
> >
> >>
> >>
> >> Thanks, will give it a shot. So I should download 0.94.7 (latest stable)
> >> and run the patch tool on top with the backport? This is a little new to me.
> >>
> >> Also, I was looking at the stack below. From my reading of the code, the
> >> HTable.batch() call will always cause the prefetch call to occur, which
> >> will cause a new HTable object to get created. The constructor used in
> >> creating a new thread pool. So every call to batch will create a new
> >> thread? Or the HTable's thread pool never gets used as the pool is only
> >> used for writes? I think I am missing something but just want to confirm.
> >>
> >> Thanks
> >> Kireet

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