RFR: JDK-8215624 add parallel heap inspection support for jmap histo(G1)(Internet mail)

linzang(臧琳) linzang at tencent.com
Wed Feb 19 01:40:34 UTC 2020

Re-post this RFR with correct enhancement number to make it trackable.
please ignore the previous wrong post. sorry for troubles. 

webrev: http://cr.openjdk.java.net/~lzang/jmap-8214535/8215624/webrev_01/
bug: https://bugs.openjdk.java.net/browse/JDK-8215624
CSR: https://bugs.openjdk.java.net/browse/JDK-8239290
>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.
>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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