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From Jeff Hammerbacher <ham...@cloudera.com>
Subject Re: Hbase read performance with increasing number of client threads
Date Fri, 20 Aug 2010 06:51:10 GMT
Hey Ryan,

Could you point to the particular JIRA issues for the DFS client that are
causing these performance issues for HBase? Knowing is half the battle.

Thanks,
Jeff

On Thu, Aug 19, 2010 at 9:20 PM, Ryan Rawson <ryanobjc@gmail.com> wrote:

> Due to DFS client things are a little not as good as they should be...
> They are being worked on, so it will get resolved in time.
>
> In the mean time, the key to fast access is caching... ram ram ram.
>
> -ryan
>
> On Thu, Aug 19, 2010 at 10:15 AM, Abhijit Pol <apol@rocketfuelinc.com>
> wrote:
> > We are using Hbase 0.20.5 drop with latest cloudera Hadoop distribution.
> >
> > - We are hitting 3 nodes Hbase cluster from a client which has 10
> > threads each with thread local copy of HTable client object and
> > established connection to server.
> > - Each of 10 threads issuing 10,000 read requests of keys randomly
> > selected from pool of 1000 keys. All keys are present on HBase and
> > table is pinned in memory (to make sure we don't have any disk seeks).
> > - If we run this test with 10 threads we get avg latency as seen by
> > client = 8ms (excluding initial 10 connection setup time) . But if we
> > increase # threads to 100, 250 to 500 we get increasing latency
> > numbers like 26ms, 51ms, 90ms.
> > - We have enabled HBase metrics on RS and we see "get_avg_time" on all
> > RS between 5-15ms in all tests, consistently.
> >
> > Is this expected? Any tips to get consistent performance below 20ms?
> >
>

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