longer ParNew collection in JDK8?

[Staffan Friberg]

Hi Joy,

Could you try with the following extra option, it would change the 
setting to be similar in JDK 7 as they are in JDK 6.

-XX:+UnlockExperimentalVMOptions -XX:WorkStealingYieldsBeforeSleep=1000

//Staffan

On 02/02/2015 10:38 AM, Joy Xiong wrote:
> Hi Jon,
>
> Yes, most objects in my application die young and very little 
> promoted. As you can see from the attached figure (the occupied heap 
> size from Sep 28 to Nov 11), CMS happened very rare. However, it seems 
> two releases do not have much difference in promotion rate, as they 
> have same number of CMS in the log.
>
> We have the same JVM parameters for both releases as below:
>
> CommandLine flags: -XX:+AlwaysPreTouch 
> -XX:CMSInitiatingOccupancyFraction=70 -XX:ErrorFile=logs/hs_err.log 
> -XX:InitialHeapSize=34271657984 -XX:+ManagementServer 
> -XX:MaxHeapSize=34271657984 -XX:MaxNewSize=2147483648 
> -XX:NewSize=2147483648 -XX:OldPLABSize=16 -XX:+PrintGC 
> -XX:+PrintGCApplicationConcurrentTime 
> -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCDateStamps 
> -XX:+PrintGCDetails -XX:+PrintGCTimeStamps 
> -XX:+PrintTenuringDistribution -XX:SurvivorRatio=2 
> -XX:+UnlockDiagnosticVMOptions -XX:+UseCompressedClassPointers 
> -XX:+UseCompressedOops -XX:+UseConcMarkSweepGC -XX:+UseParNewGC
>
> thanks,
> -Joy
>
>
> On Monday, February 2, 2015 10:06 AM, Jon Masamitsu 
> <jon.masamitsu at oracle.com> wrote:
>
>
> Joy,
>
> Is your application such that most everything dies in the
> young generation and very little is promoted?  If yes,
> do you know if there is a difference in how much is
> promoted between the two releases?
>
> Jon
>
> On 01/29/2015 10:27 AM, Joy Xiong wrote:
>>
>> Hi,
>>
>> We recently move our services from JDK6 to JDK8, but observe longer 
>> ParNew GC pause in JDK8. For example, the pause time increase from 
>> 27ms to 43ms in one service. The service has the JVM parameters as below:
>> -Xms32684m -Xmx32684m -XX:NewSize=2048m -XX:MaxNewSize=2048m 
>> -XX:+UseConcMarkSweepGC -XX:+UseParNewGC 
>> -XX:CMSInitiatingOccupancyFraction=70 -XX:SurvivorRatio=2 
>> -XX:+AlwaysPreTouch -XX:+UseCompressedOops 
>> -XX:+PrintTenuringDistribution -XX:+PrintGCDetails 
>> -XX:+PrintGCDateStamps -Xloggc:logs/gc.log 
>> -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCApplicationConcurrentTime
>>
>> Is this longer ParNew pause expected? Any suggestions to mitigate the 
>> longer pause?
>>
>> thanks,
>> -Joy
>>
>>
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