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From Vitalii Tymchyshyn <>
Subject Re: 1.0.6 - High CPU troubleshooting
Date Wed, 25 Jan 2012 15:09:47 GMT

What's in the logs? It should output something like "Hey, you've got 
most of your memory used. I am going to flush some of memtables". Sorry, 
I don't remember exact spelling, but it's gong from GC, so it should be 
greppable by "GC".

25.01.12 16:26, Matthew Trinneer написав(ла):
> Hello Community,
> Am troubleshooting an issue with sudden and sustained high CPU on nodes in a 3 node cluster.
 This takes place when there is minimal load on the servers, and continues indefinitely until
I stop and restart a node.  All nodes (3) seem to be effected by the same issue, however it
doesn't occur simultaneous on them (although all potentially could be effected at the same
> Here's what I've been doing to troubleshoot.
> * vmstat - have run on all servers and there is *no* swap going on
> * iostat - have run on all servers and there is no indication that the disk is in anyway
a bottleneck
> * nodetool - nothing is backed up.  Not using all available heap (about 2/3rds).
> * Have tracked it down to a specific thread (top -H).  When I find that thread's hex
equivalent in a jstack dump I see the following
> 	"Concurrent Mark-Sweep GC Thread" prio=10 tid=0x0000000001d48800 nid=0x4534 runnable
> Which makes me think that perhaps it's something to do with GC configuration.   Unfortunately
I'm not able to determine why this might be happening.  Any suggestions on how to continue
> btw - here's my jvm (just in case)
> java version "1.6.0_22"
> Java(TM) SE Runtime Environment (build 1.6.0_22-b04)
> Java HotSpot(TM) 64-Bit Server VM (build 17.1-b03, mixed mode)
> Thanks!
> Matt

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