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HBase, mail # dev - HBase read perfomnance and HBase client


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Re: HBase read perfomnance and HBase client
Varun Sharma 2013-08-01, 06:37
Last time around, we found that block checksums was #1 (but then if we are
serving from block cache, it should not matter) and binarysearch into
indices was also high in terms of CPU.

We use a multi level index for HFile v2 right ? Is that just a multi level
binary search on all the start keys of data blocks or do we ever sequential
scan index blocks like we do for data blocks...
On Wed, Jul 31, 2013 at 11:15 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:

> Yeah, that would seem to indicate that seeking into the block is not a
> bottleneck (and you said earlier that everything fits into the blockcache).
> Need to profile to know more. If you have time, would be cool if you can
> start jvisualvm and attach it to the RS start the profiling and let the
> workload run for a bit.
>
> -- Lars
>
>
>
> ----- Original Message -----
> From: Vladimir Rodionov <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]; lars hofhansl <[EMAIL PROTECTED]>
> Cc:
> Sent: Wednesday, July 31, 2013 9:57 PM
> Subject: Re: HBase read perfomnance and HBase client
>
> Smaller block size (32K) does not give any performance gain and this is
> strange, to say the least.
>
>
> On Wed, Jul 31, 2013 at 9:33 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:
>
> > Would be interesting to profile MultiGet. With RTT of 0.1ms, the internal
> > RS friction is probably the main contributor.
> > In fact MultiGet just loops over the set at the RS and calls single gets
> > on the various regions.
> >
> > Each Get needs to reseek into the block (even when it is cached, since
> KVs
> > have variable size).
> >
> > There are HBASE-6136 and HBASE-8362.
> >
> >
> > -- Lars
> >
> > ________________________________
> > From: Vladimir Rodionov <[EMAIL PROTECTED]>
> > To: [EMAIL PROTECTED]; lars hofhansl <[EMAIL PROTECTED]>
> > Sent: Wednesday, July 31, 2013 7:27 PM
> > Subject: Re: HBase read perfomnance and HBase client
> >
> >
> > Some final numbers :
> >
> > Test config:
> >
> > HBase 0.94.6
> > blockcache=true, block size = 64K, KV size = 62 bytes (raw).
> >
> > 5 Clients: 96GB, 16(32) CPUs (2.2Ghz), CentOS 5.7
> > 1 RS Server: the same config.
> >
> > Local network with ping between hosts: 0.1 ms
> >
> >
> > 1. HBase client hits the wall at ~ 50K per sec regardless of # of CPU,
> > threads, IO pool size and other settings.
> > 2. HBase server was able to sustain 170K per sec (with 64K block size).
> All
> > from block cache. KV size = 62 bytes (very small). This is for single Get
> > op, 60 threads per client, 5 clients (on different hosts)
> > 3. Multi - get hits the wall at the same 170K-200K per sec. Batch size
> > tested: 30, 100. The same performance absolutely as with batch size = 1.
> > Multi get has some internal issues on RegionServer side. May be excessive
> > locking or some thing else.
> >
> >
> >
> >
> >
> > On Tue, Jul 30, 2013 at 2:01 PM, Vladimir Rodionov
> > <[EMAIL PROTECTED]>wrote:
> >
> > > 1. SCR are enabled
> > > 2. Single Configuration for all table did not work well, but I will try
> > it
> > > again
> > > 3. With Nagel I had 0.8ms avg, w/o - 0.4ms - I see the difference
> > >
> > >
> > > On Tue, Jul 30, 2013 at 1:50 PM, lars hofhansl <[EMAIL PROTECTED]>
> wrote:
> > >
> > >> With Nagle's you'd see something around 40ms. You are not saying 0.8ms
> > >> RTT is bad, right? Are you seeing ~40ms latencies?
> > >>
> > >> This thread has gotten confusing.
> > >>
> > >> I would try these:
> > >> * one Configuration for all tables. Or even use a single
> > >> HConnection/Threadpool and use the HTable(byte[], HConnection,
> > >> ExecutorService) constructor
> > >> * disable Nagle's: set both ipc.server.tcpnodelay and
> > >> hbase.ipc.client.tcpnodelay to true in hbase-site.xml (both client
> *and*
> > >> server)
> > >> * increase hbase.client.ipc.pool.size in client's hbase-site.xml
> > >> * enable short circuit reads (details depend on exact version of
> > Hadoop).
> > >> Google will help :)
> > >>
> > >> -- Lars
> > >>
> > >>
> > >> ----- Original Message -----