G1gc compaction algorithm

[Martin Makundi]

Hi!

Here are the fresh logs:

http://81.22.250.165/log/gc-16m-2014-08-04.log

Today we were hit by quite some number of Full GC's with quite short
intervals and as can be suspected, not so happy users ;)

Any ideas? I will reduce the region size to 4M for now, because it resulted
in much fewer full gcs.

**
Martin


2014-08-01 1:17 GMT+03:00 Martin Makundi <martin.makundi at koodaripalvelut.com
>:

> Hmm.. ok, I copy pasted if from the mail, it works after typing manually,
> thanks.
>
> Problem seems to have been BOTH a whitespace typo AND
> UnlockDiagnosticOptions was on the right side.
>
> Thanks.
>
> Gathering logs now.
>
> **
> Martin
>
>
> 2014-08-01 1:01 GMT+03:00 Yu Zhang <yu.zhang at oracle.com>:
>
>  maybe some hidden text?
>>
>> Thanks,
>> Jenny
>>
>> On 7/31/2014 2:52 PM, Martin Makundi wrote:
>>
>> Strange that it is in the property summary but doesn't allow setting it.
>>
>>
>> 2014-08-01 0:39 GMT+03:00 Martin Makundi <
>> martin.makundi at koodaripalvelut.com>:
>>
>>> Hi!
>>>
>>> UnlockDiagnosticVMOptions  is on (though later (on the right side) in
>>> the command line). Jvm version is
>>>
>>>  java version "1.7.0_55"
>>> Java(TM) SE Runtime Environment (build 1.7.0_55-b13)
>>> Java HotSpot(TM) 64-Bit Server VM (build 24.55-b03, mixed mode)
>>>
>>>
>>>
>>> 2014-08-01 0:37 GMT+03:00 Yu Zhang <yu.zhang at oracle.com>:
>>>
>>>  Martin,
>>>>
>>>> These 2 need to run with  -XX:+UnlockDiagnosticVMOptions
>>>>
>>>> Thanks,
>>>> Jenny
>>>>
>>>>  On 7/31/2014 2:33 PM, Martin Makundi wrote:
>>>>
>>>> Hi!
>>>>
>>>>  G1SummarizeRSetStats does not seem to work, jvm says:
>>>>
>>>>  Improperly specified VM option 'G1SummarizeRSetStatsPeriod=10'
>>>> Error: Could not create the Java Virtual Machine.
>>>> Error: A fatal exception has occurred. Program will exit.
>>>>
>>>>  Same for both new options
>>>>
>>>>
>>>>
>>>> 2014-07-31 20:22 GMT+03:00 Yu Zhang <yu.zhang at oracle.com>:
>>>>
>>>>> Martin,
>>>>>
>>>>> The ScanRS for mixed gc is extremely long, 1000-9000ms.  Because it is
>>>>> over pause time goal, minimum old regions can be added to CSet.  So mixed
>>>>> gc is not keeping up.
>>>>>
>>>>> Can do a run keeping 16m region size,  no G1PrintRegionLivenessInfo,
>>>>> no PrintHeapAtGC.  But -XX:+G1SummarizeRSetStats
>>>>> -XX:G1SummarizeRSetStatsPeriod=10
>>>>>
>>>>> This should tell us more about RSet information.
>>>>>
>>>>> While the UpdateRS is not as bad as ScanRS, we can try to push it to
>>>>> the concurrent threads.  Can you add -XX:G1RSetUpdatingPauseTimePercent=5.
>>>>>  I am hoping this brings the UpdateRS down to 50ms.
>>>>>
>>>>>
>>>>> Thanks,
>>>>> Jenny
>>>>>
>>>>> On 7/28/2014 8:27 PM, Martin Makundi wrote:
>>>>>
>>>>>> Hi!
>>>>>>
>>>>>> We suffered a couple of Full GC's using regionsize 5M (it seems to be
>>>>>> exact looking at logged actual parameters) and we tried the 16M option and
>>>>>> this resulted in more severe Full GC behavior.
>>>>>>
>>>>>> Here is the promised log for 16 M setting:
>>>>>> http://81.22.250.165/log/gc-16m.log
>>>>>>
>>>>>> We switch back to 5M hoping it will behave more nicely.
>>>>>>
>>>>>> **
>>>>>> Martin
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>>
>
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