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From Gautam Kowshik <gautamkows...@gmail.com>
Subject Re: Increasing write throughput..
Date Fri, 31 Oct 2014 18:16:06 GMT
- Sorry bout the raw image upload, here’s the tsdb snapshot : http://postimg.org/image/gq4nf96x9/
- Hbase version 98.1 (CDH 5.1 distro)
- hbase-site pastebin : http://pastebin.com/fEctQ3im
- this table ‘msg' has been pre-split with 240 regions and writes are evenly distributed
into 240 buckets. ( the bucket is a prefix to the row key ) . These regions are well spread
across the 8 RSs. Although over time these 240 have split and now become 2440 .. each region
server has ~280 regions.
- last 500 lines of log from one RS : http://pastebin.com/8MwYMZPb Al
- no hot regions from what i can tell. 

One of my main concerns was why even after setting the memstore flush size to 512M is it still
flushing at 128M. Is there a setting i’v missed ? I’l try to get more details as i find
them.

Thanks and Cheers,
-Gautam.

On Oct 31, 2014, at 10:47 AM, Stack <stack@duboce.net> wrote:

> What version of hbase (later versions have improvements in write
> throughput, especially when many writing threads).  Post a pastebin of
> regionserver log in steadystate if you don't mind.  About how many writers
> going into server at a time?  How many regions on server.  All being
> written to at same rate or you have hotties?
> Thanks,
> St.Ack
> 
> On Fri, Oct 31, 2014 at 10:22 AM, Gautam <gautamkowshik@gmail.com> wrote:
> 
>> I'm trying to increase write throughput of our hbase cluster. we'r
>> currently doing around 7500 messages per sec per node. I think we have room
>> for improvement. Especially since the heap is under utilized and memstore
>> size doesn't seem to fluctuate much between regular and peak ingestion
>> loads.
>> 
>> We mainly have one large table that we write most of the data to. Other
>> tables are mainly opentsdb and some relatively small summary tables. This
>> table is read in batch once a day but otherwise is mostly serving writes
>> 99% of the time. This large table has 1 CF and get's flushed at around
>> ~128M fairly regularly like below..
>> 
>> {log}
>> 
>> 2014-10-31 16:56:09,499 INFO org.apache.hadoop.hbase.regionserver.HRegion:
>> Finished memstore flush of ~128.2 M/134459888, currentsize=879.5 K/900640
>> for region
>> msg,00102014100515impression\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x002014100515040200049358\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x004138647301\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0002e5a329d2171149bcc1e83ed129312b\x00\x00\x00\x00,1413909604591.828e03c0475b699278256d4b5b9638a2.
>> in 640ms, sequenceid=16861176169, compaction requested=true
>> 
>> {log}
>> 
>> Here's a pastebin of my hbase site : http://pastebin.com/fEctQ3im
>> 
>> What i'v tried..
>> -  turned of major compactions , and handling these manually.
>> -  bumped up heap Xmx from 24G to 48 G
>> -  hbase.hregion.memstore.flush.size = 512M
>> - lowerLimit/ upperLimit on memstore are defaults (0.38 , 0.4) since the
>> global heap has enough space to accommodate the default percentages.
>> - Currently running Hbase 98.1 on an 8 node cluster that's scaled up to
>> 128GB RAM.
>> 
>> 
>> There hasn't been any appreciable increase in write perf. Still hovering
>> around the 7500 per node write throughput number. The flushes still seem to
>> be hapenning at 128M (instead of the expected 512)
>> 
>> I'v attached a snapshot of the memstore size vs. flushQueueLen. the block
>> caches are utilizing the extra heap space but not the memstore. The flush
>> Queue lengths have increased which leads me to believe that it's flushing
>> way too often without any increase in throughput.
>> 
>> Please let me know where i should dig further. That's a long email, thanks
>> for reading through :-)
>> 
>> 
>> 
>> Cheers,
>> -Gautam.
>> 


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