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From Anoop John <anoop.hb...@gmail.com>
Subject Re: Hbase regionserver.MultiVersionConcurrencyControl Warning
Date Wed, 10 Aug 2016 06:10:31 GMT
Ya it comes with write workload.  Not like with concurrent reads.
Once the write is done (memstore write and WAL write), we mark that
MVCC operation corresponding to this as complete and wait for a global
read point to advance to atleast this point. (Every write op will have
a number corresponding to its mvcc op)
As the mvcc op begin, the write entries (which is having this number)
added to a Q.  Once write is over and we complete the mvcc op, we will
mark the entry corresponding to it (It is in Q now) as completed/done.
  So there are other entries also in the Q corresponding to other
parallel writes.   Now we will try to move the global read point at
least upto this mark.  Means we will have to make sue all the write
ops with lesser number than this to get completed.  Until then , there
is a wait.   So what is happening here is a later write op is
completed and that is still waiting for an older write to get
completed.   What sort of write ops u have?   Batch put and/or
increment/append?

-Anoop-


On Tue, Aug 9, 2016 at 6:45 PM, Sterfield <sterfield@gmail.com> wrote:
> 2016-08-05 17:52 GMT+02:00 Bryan Beaudreault <bbeaudreault@hubspot.com>:
>
>> I'm also interested in an answer here. We see this from time to time in our
>> production HBase clusters (non-opentsdb). It seems to be related to
>> contention under heavy reads or heavy writes. But it's not clear what the
>> impact is here.
>>
>> On Fri, Aug 5, 2016 at 5:14 AM Sterfield <sterfield@gmail.com> wrote:
>>
>> > Hi,
>> >
>> > I'm currently testing Hbase 1.2.1 + OpenTSDB. For that, I'm generating a
>> > high load of HTTP PUT on OpenTSDB, which then writes in Hbase. Currently,
>> > I'm able to feed 300k data point per seconds, and I'm trying to achieve
>> > higher speed.
>> >
>> > I have also activate JMX on both Master and Region servers in order to
>> grab
>> > a bunch of metrics from Hbase.
>> >
>> > At some point, I'm noticing a bunch of warnings in a region server log
>> file
>> > :
>> >
>> > 2016-08-04 05:12:06,537 WARN
>> >  [B.defaultRpcServer.handler=21,queue=3,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714778}
>> > 2016-08-04 05:12:06,538 WARN
>> >  [B.defaultRpcServer.handler=19,queue=1,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714778}
>> > 2016-08-04 05:12:06,538 WARN
>> >  [B.defaultRpcServer.handler=40,queue=4,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714778}
>> > 2016-08-04 05:12:06,548 WARN
>> >  [B.defaultRpcServer.handler=0,queue=0,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714778}
>> > 2016-08-04 05:12:06,549 WARN
>> >  [B.defaultRpcServer.handler=35,queue=5,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714778}
>> > 2016-08-04 05:12:06,556 WARN
>> >  [B.defaultRpcServer.handler=7,queue=1,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714779}
>> > 2016-08-04 05:12:06,558 WARN
>> >  [B.defaultRpcServer.handler=20,queue=2,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714779}
>> > 2016-08-04 05:12:06,559 WARN
>> >  [B.defaultRpcServer.handler=14,queue=2,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714779}
>> > 2016-08-04 05:12:06,609 WARN
>> >  [B.defaultRpcServer.handler=42,queue=0,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714779}
>> > 2016-08-04 05:12:06,609 WARN
>> >  [B.defaultRpcServer.handler=32,queue=2,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714779}
>> > 2016-08-04 05:12:06,619 WARN
>> >  [B.defaultRpcServer.handler=2,queue=2,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714779}
>> > 2016-08-04 05:12:06,619 WARN
>> >  [B.defaultRpcServer.handler=48,queue=0,port=16020]
>> > regionserver.MultiVersionConcurrencyControl: STUCK:
>> > MultiVersionConcurrencyControl{readPoint=7714719, writePoint=7714779}
>> >
>> > Can someone shed some lights on this ? I've googling + searching the
>> > documentation, but found no clue on this subject.
>> >
>> > Is it a problem ? If so, how can I fix it ?
>> >
>> > Thanks a lot for your help,
>> >
>> > Guillaume
>> >
>>
>
> Hello,
>
> Sorry to bump this thread, but no one knows anything about this issue ?
>
> Thanks,
>
> Guillaume

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