RFR: add parallel heap inspection support for jmap histo(G1)(Internet mail)

serguei.spitsyn at oracle.com serguei.spitsyn at oracle.com
Tue Feb 18 20:59:10 UTC 2020


Hi Lin,

Could you, please, re-post your RFR with the right enhancement number in 
the message subject?
It will be more trackable this way.

Thanks,
Serguei


On 2/17/20 10:29 PM, linzang(臧琳) wrote:
> Dear David,
>        Thanks a lot!
>        I have updated the refined code to http://cr.openjdk.java.net/~lzang/jmap-8214535/8215264/webrev_01/.
>        IMHO the parallel heap inspection can be extended to all kinds of heap as long as the heap layout can support parallel iteration.
>        Maybe we can firstly use this webrev to discuss how to implement it, because I am not sure my current implementation is an appropriate way to communicate with collectedHeap, then we can extend the solution to other kinds of heap.
>     
> Thanks,
> --------------
> Lin
>> Hi Lin,
>>
>> Adding in hotspot-gc-dev as they need to see how this interacts with GC
>> worker threads, and whether it needs to be extended beyond G1.
>>
>> I happened to spot one nit when browsing:
>>
>> src/hotspot/share/gc/shared/collectedHeap.hpp
>>
>> +   virtual bool run_par_heap_inspect_task(KlassInfoTable* cit,
>> +                                          BoolObjectClosure* filter,
>> +                                          size_t* missed_count,
>> +                                          size_t thread_num) {
>> +     return NULL;
>>
>> s/NULL/false/
>>
>> Cheers,
>> David
>>
>> On 18/02/2020 2:15 pm, linzang(臧琳) wrote:
>>> Dear All,
>>>         May I ask your help to review the follow changes:
>>>         webrev:
>>> http://cr.openjdk.java.net/~lzang/jmap-8214535/8215264/webrev_00/
>>>       bug: https://bugs.openjdk.java.net/browse/JDK-8215624
>>>       related CSR: https://bugs.openjdk.java.net/browse/JDK-8239290
>>>         This patch enable parallel heap inspection of G1 for jmap histo.
>>>         my simple test shown it can speed up 2x of jmap -histo with
>>> parallelThreadNum set to 2 for heap at ~500M on 4-core platform.
>>>
>>> ------------------------------------------------------------------------
>>> BRs,
>>> Lin
> >



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