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From Esteban Gutierrez <este...@cloudera.com>
Subject Re: HBase monitoring
Date Thu, 02 Jul 2015 06:44:58 GMT
Hi Wojciech,

>From the memory metrics and the up time of the RS reported by top seems
that JVM has been running for a while, so a good part of the memory pages
available for the JVM process have been touched and now are considered as
used by to OS. Same thing can happen if -Xms is present and its larger than
the default or equal to -Xmx causing those memory pages to be "touched" and
considered by the OS as used even when the JVM hasn't claimed that memory
for object creation.

BTW, usually when you monitor memory utilization by HBase, you only monitor
the JVM metrics and not the memory usage reported by the OS for the HBase
process, since that usually is (or will become) a constant value during the
life of the process.

I hope that helps.

esteban.




--
Cloudera, Inc.


On Wed, Jun 24, 2015 at 2:27 AM, Wojciech Indyk <wojciechindyk@gmail.com>
wrote:

> hello!
> I try to monitor memory of my regionservers. I have HBase 0.98 on CDH
> 5.3.1.
> I can see inconsistency between HBase metrics (here is metrics dump
> from HBase UI):
> "name" : "Hadoop:service=HBase,name=JvmMetrics",
>     "modelerType" : "JvmMetrics",
>     "tag.Context" : "jvm",
>     "tag.ProcessName" : "IPC",
>     "tag.SessionId" : "",
>     "tag.Hostname" : "sqhadoop04.gazeta.pl",
>     "MemNonHeapUsedM" : 93.26676,
>     "MemNonHeapCommittedM" : 94.89844,
>     "MemNonHeapMaxM" : -9.536743E-7,
>     "MemHeapUsedM" : 8513.122,
>     "MemHeapCommittedM" : 20330.25,
>     "MemHeapMaxM" : 20330.25,
>     "MemMaxM" : 20330.25,
> and system "top" monitoring (all of my hbase processes on the
> regionserver):
> PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 19700 hbase     20   0 22.3g  16g  23m S  1.3  8.7 479:47.53 java
> 19874 hbase     20   0  107m 2404  556 S  0.7  0.0   9:16.13 hbase.sh
> 19873 hbase     20   0  105m  908  556 S  0.0  0.0   0:00.00 hbase.sh
>
> As we can see there is 16GB according to "top" and ~8.5GB according to
> HBase. Why these values are different?
>
> Kindly regards
> Wojciech Indyk
>

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