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Posted to issues@hbase.apache.org by "Lars Hofhansl (JIRA)" <ji...@apache.org> on 2013/06/07 00:46:21 UTC
[jira] [Resolved] (HBASE-8698) potential thread creation in
MetaScanner.metaScan
[ https://issues.apache.org/jira/browse/HBASE-8698?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Lars Hofhansl resolved HBASE-8698.
----------------------------------
Resolution: Invalid
> 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
>
> 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 <ki...@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 <ki...@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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