Question regarding G1 option to run parallel Old generation garbage collection?

[Kirk Pepperdine]

Hi Monica,

Can you comment on what a value of 0 means?

Regards,
Kirk

On 2012-10-19, at 2:55 PM, Monica Beckwith <monica.beckwith at oracle.com> wrote:

> Couple of quick observations and questions - 
> G1 is officially supported in 7u4. (There are numerous performance improvements that I recommend updating to the latest jdk7 update, if possible)
> What do you mean by old gen collection? Are you talking about MixedGCs?
> Instead of setting InitiatingHeapOccupancyPercent to zero, have you tried resizing your young generation?
> I see the NewRatio, but that fixes the nursery to 640, instead have you tried with a lower (than the min default) of nursery using the NewSize option?
> -Monica
> 
> 
> On 10/19/2012 12:13 AM, csewhiz wrote:
>> 
>> Hello All,
>>   Sorry for posting this question in this mailing list. I am unable to find any answer for this. I am trying to tune our application for G1GC as we need very small pauses Below 500msec.
>>   But the problem is when we are runing with G1GC (under jdk 6_u37)  Old generation of garbage collection only happening when it is reaching the Max GC size I noticed on jdk 6U 37 if max heap size is 1GB then it is close to 1sec 2GB close to 2 sec pauses.
>>  
>>   Is there any parameter to force the old gc happening regularly.
>>  
>> I am trying following setting,
>>  
>> -Xms1280M -Xmx1280M -XX:+UseG1GC -XX:MaxTenuringThreshold=15 -XX:SurvivorRatio=8 -XX:NewRatio=1 -XX:GCPauseIntervalMillis=7500 -XX:MaxGCPauseMillis=500 -XX:InitiatingHeapOccupancyPercent=0 -XX:ParallelGCThreads=7 -XX:ConcGCThreads=7
>>  
>> If anyone can give insight on how full GC is triggred internals will be of great help.
>>  
>> PS: I have tried without any option for G1 but not of much help hence .. this one trying to be agressive ? but of not much help.
>>  
>>  
>> Regards,
>> Soumit
>> 
> 
> -- 
> <oracle_sig_logo.gif>
> Monica Beckwith | Java Performance Engineer
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> Texas 
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