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From Brandon Williams <dri...@gmail.com>
Subject Re: Problems running Cassandra 0.6.1 on large EC2 instances.
Date Tue, 18 May 2010 00:00:30 GMT
On Mon, May 17, 2010 at 6:02 PM, Curt Bererton <curt@zipzapplay.com> wrote:

> So pretty much the defaults aside from the 7Gig max heap. CPU is totally
> hammered right now, and it is receiving 0 ops/sec from me since I
> disconnected it from our application right now until I can figure out what's
> going on.
>
> running top on the machine I get:
> top - 18:56:32 up 2 days, 20:57,  2 users,  load average: 14.97, 15.24,
> 15.13
> Tasks:  87 total,   5 running,  82 sleeping,   0 stopped,   0 zombie
> Cpu(s): 40.1%us, 33.9%sy,  0.0%ni,  0.1%id,  0.0%wa,  0.0%hi,  1.3%si,
> 24.6%st
> Mem:   7872040k total,  3618764k used,  4253276k free,   387536k buffers
> Swap:        0k total,        0k used,        0k free,  1655556k cached
>
>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+
> COMMAND
>  2566 cassandr  25   0 7906m 639m  10m S  150  8.3   5846:35 java
>

Since your heap isn't anywhere near exhausted, I don't think you have a GC
storm happening.  Is it one core or both that are pegged?  One way to tell
which thread is using all the CPU is to run top -H so you can see the
threads, get the pid of the one using the CPU, convert that to hex, then run
jmap <main java pid> and grep for the hex.

-Brandon

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