Hung JVM consuming 100% CPU

Jon Masamitsu jon.masamitsu at
Wed Mar 2 10:45:22 PST 2011

Kirk, you're right!  The MinFreeRatio and MaxFreeRatio do result in an
initiating occupancy as you describe.  Does seem like a concurrent
collection should have started.

On 3/1/2011 9:06 PM, Charles K Pepperdine wrote:
> Hi Jon,
>> I don't see CMSInitiatingOccupancyFraction on the command line.
>>         -Xmx896m -Xss128k -XX:NewSize=384M -XX:MaxPermSize=96m
>>         -XX:+UseParNewGC -XX:+UseConcMarkSweepGC
>> so CMS isn't using occupancy of the tenured gen to start a cycle. 
>> That is the
>> default behavior.
> Ok, I'm trying to understand what you are saying. It was my 
> understanding that CMS is initiated when tenured reaches a value of 
> 68% = current occupancy +  the anticipated promotions. So are you 
> saying that setting the initiating occupancy fraction doesn't override 
> that value, it completely changes how CMS is triggered? Is the 
> flag UseCMSInitiatingOccupancyOnly only valid when you 
> use CMSInitiatingOccupancyFraction or does that flag also use 
> anticipated promotions as part of it's calculation?
> TIA,
> Kirk
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