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From "Liu, Ming (HPIT-GADSC)" <ming.l...@hp.com>
Subject RE: how to tell there is a OOM in regionserver
Date Tue, 02 Dec 2014 06:37:56 GMT
Thank you both!

Yes, I can see there is the '.out' file with clear proof of process was 'killed'. So we can
prove this issue now!
And it is also true that we must rely on JVM itself for proof that the kill operation is due
to OOM. 
Thank you both, this is a very good learning.

Thanks,
Ming

-----Original Message-----
From: Bharath Vissapragada [mailto:bharathv@cloudera.com] 
Sent: Tuesday, December 02, 2014 2:00 PM
To: hbase-user
Subject: Re: how to tell there is a OOM in regionserver

I agree with Otis' response. Adding a few more details, there is a ".out"
 file in the logs/ directory, that is the stdout for each of these daemons and incase of 
an OOM crash, it prints something like this

# java.lang.OutOfMemoryError: Java heap space

# -XX:OnOutOfMemoryError="kill -9 %p"

#   Executing /bin/sh -c "kill -9 <pid>"...



On Tue, Dec 2, 2014 at 11:06 AM, Otis Gospodnetic < otis.gospodnetic@gmail.com> wrote:

> Hi Ming,
>
> 1) There typically is an OOM message from the JVM itself
>
> 2) I would monitor the server instead of relying on log messages 
> mentioning OOMs.  For example, in SPM <http://sematext.com/spm/> we 
> have "hearbeat alerts" that tell us when we stop hearing from 
> RegionServers and other types of servers.  It also helps when servers 
> simply die for reasons other than OOM.
>
> 3) You could (should?) monitor individual memory pools and possibly 
> set alerts or anomaly detection on those.  If you have that, if there 
> was an OOM, you will typically see one of the memory pools approach 
> 100% utilization.  I personally really like this report in SPM because 
> it gives a bit more insight than just "heap size/utilization".  So I'd 
> point the admin to this sort of monitoring report.
>
> 4) High GC counts/time, or jump in those metrics, and then typically 
> also jump in CPU usage is what often precedes OOMs.
>
> Otis
> --
> Monitoring * Alerting * Anomaly Detection * Centralized Log Management 
> Solr & Elasticsearch Support * http://sematext.com/
>
>
> On Tue, Dec 2, 2014 at 12:22 AM, Liu, Ming (HPIT-GADSC) 
> <ming.liu2@hp.com>
> wrote:
>
> > Hi, all,
> >
> > Recently, one of our HBase 0.98.5 instance meet with issues: when 
> > run
> some
> > specific workload, all region servers will suddenly shut down at 
> > same
> time,
> > but master is still running. When I check the log, in master log, I 
> > can
> see
> > messages like
> > 2014-12-01 08:28:11,072 DEBUG [main-EventThread] master.ServerManager:
> > Added=n008.cluster,60020,1417413986550 to dead servers, submitted
> shutdown
> > handler to be executed meta=false
> > And on n008, regionserver log file, there is no ERROR message, the 
> > last log entry looks very like a ZooKeeper startup message. The log 
> > just
> stopped
> > with that last ZooKeeper startup message, and the Region Server 
> > process
> was
> > gone when we check with 'jps'.
> >
> > We then increased the heap size of regionserver, and it work fine.
> > RegionServer no longer disappear. So we doubt there was a Out Of 
> > Memory issue, so the region server processes are killed. But my questions are:
> >
> > 1.       What log message will indicate there is a OOM? Since the region
> > server is 'kill -9', so I think there is no message can tell this.
> >
> > 2.       If there is no typical log message about OOM, then how can an
> > admin make sure there is a region server OOM happened? We just 
> > guess, but can not make sure. We hope there is a method to tell OOM 
> > occured for
> sure.
> >
> > 3.       Does the Zookeeper message appears every time with RegionServer
> > OOM (if it is a OOM). Or it is just a random event just in our system?
> >
> > So in sum, I want to know what is the typical clue that people can 
> > make sure there is a OOM issue in HBase region server?
> >
> > Thank you,
> > Ming
> >
>



--
Bharath Vissapragada
<http://www.cloudera.com>
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