Question about Object Copy times

Fri Aug 21 04:32:22 UTC 2015

Machines are mostly 192 GB, max we can go 10 or 20 GB more, we have a old
gen objects (which is what live means right?) of around 40 ish GB size
other than that every thing is per request churn (short lived objects).
Does going for even bigger heap help in this scenario ?

Thanks

On Thu, Aug 20, 2015 at 9:04 PM, Tao Mao <yiyeguhu at gmail.com> wrote:

> Hi,
>
> Is 140~150GB your memory limit? What's your ballpark live data set size?
> Since you are looking to improve throughput, it may be helpful to increase
> maxheapsize.
>
> Thanks.
> Tao Mao
>
>
> On Thu, Aug 20, 2015 at 8:21 PM, D vd Reddy <dvdeepankar.reddy at gmail.com>
> wrote:
>
>> Hi,
>>
>> I have enable -XX:+PrintTenuringDistribution -XX:+PrintAdaptiveSizePolicy
>> and moved to a newer build (1.8.0_45). No major improvements but I am
>> seeing new information.
>>
>> Also Is the Desired Survivor Size printed by Tenuring Distribution only a
>> approximate value ? I am seeing it is significantly lower than the final
>> Survivor Size.
>>
>> The new logs are here :
>> https://gist.github.com/dvdreddy/1cb9829e526d419d8452
>>
>> Thanks
>>
>> PS: I am starting new experiment with lower max pause, will post results
>> later.
>>
>>
>>
>>
>>
>>
>>
>> On Thu, Aug 20, 2015 at 6:24 PM, D vd Reddy <dvdeepankar.reddy at gmail.com>
>> wrote:
>>
>>> Thanks, I will add the -XX:+PrintAdaptiveSizePolicy, and will try to
>>> move the jvm
>>>
>>> But about the old gen getting full, there is a contradicting point that
>>> the overall heap size is going down at the same size as the size of eden
>>> minus size of survivor, So I feel that the old size is not going up by
>>> that much. Also in the logs I saw that Mixed GC is not happening that
>>> frequently only 8 mixed compared to 380 young.
>>>
>>> Am I missing something here ?
>>>
>>>
>>> Thanks,
>>>
>>>
>>> On Thu, Aug 20, 2015 at 6:14 PM, Yu Zhang <yu.zhang at oracle.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> can you reduce MaxGCPauseMillis to ~300 or 200, 1000 maybe too high,
>>>> and the eden size is ~80g, survivor size 2.5g. This might make the old gen
>>>> getting full quicker so more mixed gc, but worth a try. Also, if you can
>>>> add -XX:+PrintAdaptiveSizePolicy, it might tell us more.
>>>>
>>>> It seems you are on an older version of jvm. can you move to later
>>>> jdk8u40 or jdk8u60?
>>>>
>>>> Thanks,
>>>> Jenny
>>>>
>>>> On 8/20/2015 5:27 PM, D vd Reddy wrote:
>>>>
>>>> Hi,
>>>>
>>>> We are running G1 GC with heap size of around 140 - 150 GB, we are
>>>> observing high object copy times during young gc (> 80 % of the total GC
>>>> time).
>>>> Is this expected or is there anything we are doing wrong.  I am not
>>>> able to find any documentation of optimizing high object copy times,
>>>> any help would be appreciated
>>>>
>>>>
>>>> CommandLine flags: -XX:+AggressiveOpts -XX:InitialHeapSize=154618822656
>>>> -XX:+ManagementServer
>>>> -XX:MaxGCPauseMillis=1000 -XX:MaxHeapSize=154618822656
>>>> -XX:MaxMetaspaceSize=268435456
>>>> -XX:MetaspaceSize=268435456 -XX:ObjectAlignmentInBytes=16
>>>> -XX:+PrintGC -XX:+PrintGCDetails -XX:+PrintGCTimeStamps
>>>> -XX:+UnlockExperimentalVMOptions
>>>> -XX:-UseCompressedOops -XX:+UseG1GC
>>>>
>>>>
>>>> Sample young GC snippet
>>>>
>>>>
>>>>
>>>> 4416.985: [GC pause (G1 Evacuation Pause) (young), 0.3180932 secs]
>>>>    [Parallel Time: 291.1 ms, GC Workers: 23]
>>>>       [GC Worker Start (ms): Min: 4416985.5, Avg: 4416985.9, Max:
>>>> 4416986.2, Diff: 0.7]
>>>>       [Ext Root Scanning (ms): Min: 1.2, Avg: 1.7, Max: 4.4, Diff: 3.2,
>>>> Sum: 38.5]
>>>>       [Update RS (ms): Min: 36.3, Avg: 39.4, Max: 40.0, Diff: 3.8, Sum:
>>>> 906.0]
>>>>          [Processed Buffers: Min: 47, Avg: 80.9, Max: 124, Diff: 77,
>>>> Sum: 1861]
>>>>       [Scan RS (ms): Min: 0.5, Avg: 1.0, Max: 1.1, Diff: 0.6, Sum: 22.5]
>>>>       [Code Root Scanning (ms): Min: 0.0, Avg: 0.0, Max: 0.0, Diff:
>>>> 0.0, Sum: 0.6]
>>>>       [Object Copy (ms): Min: 247.1, Avg: 247.2, Max: 247.5, Diff: 0.4,
>>>> Sum: 5686.4]
>>>>       [Termination (ms): Min: 0.0, Avg: 0.3, Max: 0.4, Diff: 0.4, Sum:
>>>> 7.5]
>>>>       [GC Worker Other (ms): Min: 0.0, Avg: 0.3, Max: 0.7, Diff: 0.7,
>>>> Sum: 7.6]
>>>>       [GC Worker Total (ms): Min: 289.4, Avg: 290.0, Max: 290.4, Diff:
>>>> 1.0, Sum: 6669.3]
>>>>       [GC Worker End (ms): Min: 4417275.5, Avg: 4417275.8, Max:
>>>> 4417276.2, Diff: 0.7]
>>>>    [Code Root Fixup: 0.4 ms]
>>>>    [Code Root Migration: 0.5 ms]
>>>>    [Clear CT: 9.3 ms]
>>>>    [Other: 16.8 ms]
>>>>       [Choose CSet: 0.0 ms]
>>>>       [Ref Proc: 3.7 ms]
>>>>       [Ref Enq: 0.1 ms]
>>>>       [Free CSet: 6.0 ms]
>>>>    [Eden: 80.3G(80.3G)->0.0B(81.7G) Survivors: 2944.0M->2176.0M Heap:
>>>> 126.4G(144.0G)->45.4G(144.0G)]
>>>>  [Times: user=6.84 sys=0.01, real=0.32 secs]
>>>>
>>>> Full GC Log for a period of run :
>>>> https://gist.github.com/dvdreddy/5ecf9a58a3f309e8bb60
>>>>
>>>>
>>>> Thanks in advance
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> hotspot-gc-use mailing listhotspot-gc-use at openjdk.java.nethttp://mail.openjdk.java.net/mailman/listinfo/hotspot-gc-use
>>>>
>>>>
>>>>
>>>
>>
>
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