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From lars hofhansl <la...@apache.org>
Subject Re: High cpu usage on a region server
Date Thu, 12 Sep 2013 15:36:34 GMT
Yep... Very likely HBASE-9428:

8 threads:
   java.lang.Thread.State: RUNNABLE
        at java.util.Arrays.copyOf(Arrays.java:2786)
        at java.lang.StringCoding.decode(StringCoding.java:178)
        at java.lang.String.<init>(String.java:483)
        at org.apache.hadoop.hbase.filter.RegexStringComparator.compareTo(RegexStringComparator.java:96)

4 threads:
   java.lang.Thread.State: RUNNABLE
        at sun.nio.cs.ISO_8859_1$Decoder.decodeArrayLoop(ISO_8859_1.java:79)
        at sun.nio.cs.ISO_8859_1$Decoder.decodeLoop(ISO_8859_1.java:106)
        at java.nio.charset.CharsetDecoder.decode(CharsetDecoder.java:544)
        at java.lang.StringCoding$StringDecoder.decode(StringCoding.java:140)
        at java.lang.StringCoding.decode(StringCoding.java:179)
        at java.lang.String.<init>(String.java:483)
        at org.apache.hadoop.hbase.filter.RegexStringComparator.compareTo(RegexStringComparator.java:96)

It's also consistent with what you see: Lots of garbage (hence tweaking your GC options had
a significant effect)
The fix is in 0.94.12, which is in RC right now, probably to be released early next week.

-- Lars

 From: OpenSource Dev <dev.opensource@gmail.com>
To: user@hbase.apache.org 
Sent: Thursday, September 12, 2013 8:15 AM
Subject: Re: High cpu usage on a region server

A server started getting busy last night, but this time it took ~5 hrs
to get from 15% busy to 75% busy. It is not running 80% flat-out yet.
But this is still very high compared to other servers that are running
under ~25% cpu usage. Only change that I made yesterday was the
addition of "-XX:+UseParNewGC" to hbase startup command.


On Wed, Sep 11, 2013 at 2:28 PM, Stack <stack@duboce.net> wrote:
> Can you thread dump the busy server and pastebin it?
> Thanks,
> St.Ack
> On Wed, Sep 11, 2013 at 1:49 PM, OpenSource Dev <dev.opensource@gmail.com>wrote:
>> Hi,
>> I'm using HBase 0.94.6 (CDH 4.3) for Opentsdb. So far I have had no
>> issues with writes/puts. System is handles upto 800k puts per seconds
>> without issue. On average we do 250k puts per second.
>> I am having the problem with Reads, I've also isolated where the
>> problem is but not been able to find the root cause.
>> I have 16 machines running hbase-region server, each has ~35 regions.
>> Once in a while cpu goes flatout 80% in 1 region server. These are the
>> things i've noticed in ganglia:
>> hbase.regionserver.request - evenly distributed. Not seeing any spikes
>> on the busy server
>> hbase.regionserver.blockCacheSize - between 500MB and 1000MB
>> hbase.regionserver.compactionQueueSize - avg 2 or less
>> hbase.regionserver.blockCacheHitRatio - 30% on busy node, >60% on other
>> nodes
>> JVM Heap size is set to 16GB and I'm using -XX:+UseParNewGC
>> -XX:+UseConcMarkSweepGC
>> I've noticed the system load moves to a different region, sometimes
>> within a minute, if the busy region is restarted.
>> Any suggestion what could be causing the load and/or what other
>> metrics should I check ?
>> Thank you!
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