GC working well now - thanks!

[jeff.lloyd at algorithmics.com]

Hi,

 

I just wanted to say thank you very much to everyone who gave me some
time on this list.  You've been very helpful, and I believe my problem
is solved.

 

For anyone who is interested, I took the old-school approach to using
the CMS collector:  The only way to reduce the gui pauses was to make
the YG relatively small - in our case 1G.  That kept the ParNew pauses
under 1 second most of the time, and the GUI felt responsive.  However I
started getting CMS failures so I radically changed my OG size.  Since
my steady-state size is 10G, I decided to give myself a 50% buffer and
leave 5G for quick tenuring of temporary objects that survived the
ParNew YG GC.  Then since my machine has lots of physical ram I set the
initiating occupancy fraction to 50%, and the total OG size at 30G.
That's probably higher than it needs to be, but at 20G I was still
getting CMS failures followed by a full GC.  Below is the full set of GC
parameters I used:

 

-verbose:gc

XX:+PrintGCDetails

-XX:+PrintGCTimeStamps

-Xloggc:gc.txt

-XX:+PrintTenuringDistribution

-XX:+UseConcMarkSweepGC

-Xmn1g

-XX:CMSInitiatingOccupancyFraction=50

-XX:+DoEscapeAnalysis

-XX:+UseCompressedOops

 

I'm attaching the log file for anyone who may be curious to see what it
looks like.  When I view it in Visual GC the YG is very active and the
OG has long rolling hills with room to spare at the top of the hills.

 

Thanks again.

 

Jeff

 


 
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