[Building Sakai] JMX performance concerns

[Branden Visser]

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