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Re: [jetty-users] [jetty 8.0.4 and Java 1.6.0_17] periodic high CPU usage (every 5 minutes)
Thanks for the response Jaokim!
I will give that a try.

-Thanks
Vinay


On Wed, Feb 29, 2012 at 1:24 PM, Joakim Erdfelt <joakim@xxxxxxxxxxx> wrote:
Could you try 8.1.1?
It's had some significant updates with regards to nio.


Usually something like the behavior you describe would trigger me asking about your GC setup, but I can see that's configured / tweaked quite well.

--
Joakim Erdfelt

(the people behind jetty and cometd)



On Wed, Feb 29, 2012 at 2:17 PM, Vinay Pothnis <vinay.pothnis@xxxxxxxxx> wrote:
Hello,

I am seeing a periodic CPU spike when the Jetty server is handling requests. The spike occurs regularly every 5 minutes and uses up 90-100% CPU for a short duration. 
The CPU utilization falls back to normal after that short spike. This happens only when the server is receiving requests. 

I have taken thread dumps during several spikes and I have not been able to conclude anything concrete. In the dumps I observed the following:

1. There were hundreds of threads in BLOCKED state waiting for a lock held by a thread. 
2. The thread that was holding the lock was in turn BLOCKED. But it was not waiting for any other lock. Example shown below.
"qtp732533575-307956" prio=10 tid=0x00002aad980c4800 nid=0x3e1f waiting for monitor entry [0x0000000067f69000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at org.hibernate.util.SoftLimitMRUCache.get(SoftLimitMRUCache.java:74)
	- locked <0x00002aabefafa198> (a org.hibernate.util.SoftLimitMRUCache)
	at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:88)
	at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:156)
	at org.hibernate.impl.AbstractSessionImpl.getNamedQuery(AbstractSessionImpl.java:82)
	at org.hibernate.impl.SessionImpl.getNamedQuery(SessionImpl.java:1287)
	at sun.reflect.GeneratedMethodAccessor202.invoke(Unknown Source)
3. The actual lock that the threads were waiting on, varied. It was not the same in the different spikes every 5 minutes.

Environment Details:
* Embedded Jetty Version 8.0.4
* Java 1.6.0_17
* Red Hat Enterprise Linux Server release 5.2 (Tikanga)

JVM Parameters:
-server -Xmx11g -Xms11g -XX:MaxPermSize=256m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:NewSize=5g -XX:MaxNewSize=5g -XX:SurvivorRatio=6 -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -Dsun.rmi.dgc.client.gcInterval=3600000 -Dsun.rmi.dgc.server.gcInterval=3600000 

I have also attached the CPU usage pattern. Any pointers would be greatly appreciated.

Thanks!
Vinay

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