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


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Re: HBase read perfomnance and HBase client
Vladimir Rodionov 2013-07-30, 20:30
This hbase.ipc.client.tcpnodelay (default - false) explains poor single
thread performance and high latency ( 0.8ms in local network)?
On Tue, Jul 30, 2013 at 1:22 PM, Vladimir Rodionov
<[EMAIL PROTECTED]>wrote:

> One more observation: One Configuration instance per HTable gives 50%
> boost as compared to single Configuration object for all HTable's - from
> 20K to 30K
>
>
> On Tue, Jul 30, 2013 at 1:17 PM, Vladimir Rodionov <[EMAIL PROTECTED]
> > wrote:
>
>> This thread dump has been taken when client was sending 60 requests in
>> parallel (at least, in theory). There are 50 server handler threads.
>>
>>
>> On Tue, Jul 30, 2013 at 1:15 PM, Vladimir Rodionov <
>> [EMAIL PROTECTED]> wrote:
>>
>>> Sure, here it is:
>>>
>>> http://pastebin.com/8TjyrKRT
>>>
>>> epoll is not only to read/write HDFS but to connect/listen to clients as
>>> well?
>>>
>>>
>>> On Tue, Jul 30, 2013 at 12:31 PM, Jean-Daniel Cryans <
>>> [EMAIL PROTECTED]> wrote:
>>>
>>>> Can you show us what the thread dump looks like when the threads are
>>>> BLOCKED? There aren't that many locks on the read path when reading
>>>> out of the block cache, and epoll would only happen if you need to hit
>>>> HDFS, which you're saying is not happening.
>>>>
>>>> J-D
>>>>
>>>> On Tue, Jul 30, 2013 at 12:16 PM, Vladimir Rodionov
>>>> <[EMAIL PROTECTED]> wrote:
>>>> > I am hitting data in a block cache, of course. The data set is very
>>>> small
>>>> > to fit comfortably into block cache and all request are directed to
>>>> the
>>>> > same Region to guarantee single RS testing.
>>>> >
>>>> > To Ted:
>>>> >
>>>> > Yes, its CDH 4.3 . What the difference between 94.10 and 94.6 with
>>>> respect
>>>> > to read performance?
>>>> >
>>>> >
>>>> > On Tue, Jul 30, 2013 at 12:06 PM, Jean-Daniel Cryans <
>>>> [EMAIL PROTECTED]>wrote:
>>>> >
>>>> >> That's a tough one.
>>>> >>
>>>> >> One thing that comes to mind is socket reuse. It used to come up more
>>>> >> more often but this is an issue that people hit when doing loads of
>>>> >> random reads. Try enabling tcp_tw_recycle but I'm not guaranteeing
>>>> >> anything :)
>>>> >>
>>>> >> Also if you _just_ want to saturate something, be it CPU or network,
>>>> >> wouldn't it be better to hit data only in the block cache? This way
>>>> it
>>>> >> has the lowest overhead?
>>>> >>
>>>> >> Last thing I wanted to mention is that yes, the client doesn't scale
>>>> >> very well. I would suggest you give the asynchbase client a run.
>>>> >>
>>>> >> J-D
>>>> >>
>>>> >> On Tue, Jul 30, 2013 at 11:23 AM, Vladimir Rodionov
>>>> >> <[EMAIL PROTECTED]> wrote:
>>>> >> > I have been doing quite extensive testing of different read
>>>> scenarios:
>>>> >> >
>>>> >> > 1. blockcache disabled/enabled
>>>> >> > 2. data is local/remote (no good hdfs locality)
>>>> >> >
>>>> >> > and it turned out that that I can not saturate 1 RS using one
>>>> >> (comparable in CPU power and RAM) client host:
>>>> >> >
>>>> >> >  I am running client app with 60 read threads active (with
>>>> multi-get)
>>>> >> that is going to one particular RS and
>>>> >> > this RS's load is 100 -150% (out of 3200% available) - it means
>>>> that
>>>> >> load is ~5%
>>>> >> >
>>>> >> > All threads in RS are either in BLOCKED (wait) or in IN_NATIVE
>>>> states
>>>> >> (epoll)
>>>> >> >
>>>> >> > I attribute this  to the HBase client implementation which seems
>>>> to be
>>>> >> not scalable (I am going dig into client later on today).
>>>> >> >
>>>> >> > Some numbers: The maximum what I could get from Single get (60
>>>> threads):
>>>> >> 30K per sec. Multiget gives ~ 75K (60 threads)
>>>> >> >
>>>> >> > What are my options? I want to measure the limits and I do not
>>>> want to
>>>> >> run Cluster of clients against just ONE Region Server?
>>>> >> >
>>>> >> > RS config: 96GB RAM, 16(32) CPU
>>>> >> > Client     : 48GB RAM   8 (16) CPU
>>>> >> >
>>>> >> > Best regards,
>>>> >> > Vladimir Rodionov
>>>> >> > Principal Platform Engineer
>>>> >> > Carrier IQ, www.carrieriq.com