[Building Sakai] JMX performance concerns

[Branden Visser]

Hi Alan,

With Java 1.5.0_21 (most recent 1.5 version), I'm getting the same 
thing. I've pasted a snip of stdout during start-up [2].

This JVM's tuning [1] works fine in production.

Thanks,
Branden

[1] http://jira.sakaiproject.org/browse/PROD-44

[2]:

INFO: Starting up MyFaces-package : myfaces-impl in version : 1.1.5 from 
path : 
file:/sfw/sakai/sakai24/qa/clew25/tomcat1/webapps/sakai-calendar-summary-too$
INFO: MyFaces-package : tomahawk-sandbox not found. (2010-01-22 
08:41:39,606 main_org.apache.myfaces.config.FacesConfigurator)
INFO: Starting up MyFaces-package : tomahawk in version : 1.1.6 from 
path : 
file:/sfw/sakai/sakai24/qa/clew25/tomcat1/webapps/sakai-calendar-summary-tool/WE$
[Unloading class GregorSamsa$4]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa$2]
[Unloading class GregorSamsa$0]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa$0]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa$3]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa$4]
[Unloading class GregorSamsa$1]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa$1]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa]
[Unloading class GregorSamsa$2]
[Unloading class GregorSamsa$3]
INFO: Serialization provider : class 
org.apache.myfaces.shared_impl.util.serial.DefaultSerialFactory]

Berg, A.M. wrote:
> Hi Branden,
> 
> We use JMX at UvA under fire, but have not seen this. If you have not already, can you update your Java version and try again. I am very curious to hear what the issue is.
> 
> Alan
> 
> Alan Berg
> Interim QA Director - The Sakai Foundation
> 
> Senior Developer / Quality Assurance
> Group Education and Research Services
> Central Computer Services
> University of Amsterdam
> 
> http://home.uva.nl/a.m.berg
> 
> 
> 
> 
> -----Original Message-----
> From: sakai-dev-bounces at collab.sakaiproject.org on behalf of Branden Visser
> Sent: Thu 1/21/2010 17:35
> To: Sakai
> Subject: [Building Sakai] JMX performance concerns
>  
> Hi all,
> 
> I've enabled JMX on a test server, and found that it causes a lot of 
> class unloading even with no active users:
> 
> [Unloading class sun.reflect.GeneratedConstructorAccessor664]
> 
> and the server even eventually crashes:
> 
> #
> # An unexpected error has been detected by HotSpot Virtual Machine:
> #
> #  SIGSEGV (0xb) at pc=0xffffffff7e7dc8b0, pid=27373, tid=6
> #
> # Java VM: Java HotSpot(TM) 64-Bit Server VM (1.5.0_13-b05 mixed mode)
> # Problematic frame:
> # V  [libjvm.so+0x7dc8b0]
> #
> # An error report file with more information is saved as hs_err_pid27373.log
> 
> hs_err_pid27373.log suggests that it was a garbage collection thread 
> that crashed the server. I followed the instructions on confluence [1] 
> to set up remote JMX profiling.
> 
> It does this if there is nothing connected to the JMX console as well.
> 
> Any ideas?
> 
> Thanks,
> Branden
> 
> [1] 
> http://confluence.sakaiproject.org/display/QA/Remote+JVM+profiling+via+SSH+tunnels
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