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EA612: Full Garbage collection at each minor collection

Moderators: Vladimir Kondratyev, Anton Katilin

EA612: Full Garbage collection at each minor collection

Postby mschulz » Tue Jun 14, 2005 2:59 pm

When I run the application instrumented with yjp, a Full GC cycle
occurs just after each minor collection.

Is yjp doing this purposefully?

Why? Trying to reduce the memory footprint of any snapshots?

Thanks!
Martin
mschulz
 
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Postby Anton Katilin » Tue Jun 14, 2005 4:05 pm

The profiler agent does not do any explicit GCs, unless user manually presses corresponding link in the Control Panel. There were explicit GCs in previoues versions, but not in this EAP.

How did you find that?
Anton Katilin
 
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Postby mschulz » Tue Jun 14, 2005 4:40 pm

-verbose:gc -XX:+PrintGCDetails

I've set the main heap to 3GB and am still getting the Full GC cycles
way too frequently - however under load they only occur every third
GC of the young generation.

The pattern is quite different and as expected when I start the appserver without yjp.
mschulz
 
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Postby Anton Katilin » Thu Jun 16, 2005 4:07 pm

Hi,

Very interesting.
What is the exact version of JVM? (e.g. what java -version prints)

We'll consult SUN engineers regarding this issue.
Anton Katilin
 
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Postby mschulz » Sat Jun 18, 2005 9:43 pm

1.5.0_03 - Sparc 64-bit installed - running 32 bit.

The interval appears to be exactly 60s (plus the GC time),
and there's always a minor colletion followed by a full collection.

Under more load, additional minor collection are occurring.

From telemetry point of view, this is fairly convenient, as I
can look at the old generation and get to see the current state
at fixed measurement intervals.

It would be good to make such a feasure optional though.
mschulz
 
Posts: 17
Joined: Mon May 16, 2005 8:40 pm

Postby Anton Katilin » Tue Jun 21, 2005 8:30 am

I'm sorry, I don't understand which feature you mean.
Anton Katilin
 
Posts: 5966
Joined: Wed Aug 11, 2004 8:37 am


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