RFR: 8269685: Optimize HeapHprofBinWriter implementation [v8]

[Lin Zang]

On Thu, 16 Sep 2021 15:44:46 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> Lin Zang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains ten commits:
>> 
>>  - Merge branch 'master' into hprof
>>  - code clean up and refinement
>>  - Merge branch 'master' into hprof
>>  - make calculateGlobalJNIHandlesDumpRecordSize abstract
>>  - code clean up and remove useless methods
>>  - Merge branch 'master' into hprof
>>  - fix write size issue
>>  - Merge branch 'master' into hprof
>>  - 8269685: Optimize HeapHprofBinWriter implementation
>
> src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/HeapHprofBinWriter.java line 642:
> 
>> 640:     @Override
>> 641:     protected void writeHeapRecordPrologue(int size) throws IOException {
>> 642:         if (size == 0 || (currentSegmentStart > 0)) {
> 
> Formatting nit: There is no need in internal brackets `()` around `currentSegmentStart > 0`.
> Is it possible that `currentSegmentStart > 0` in the `writeHeapRecordPrologue`?
> If it is not expected then it is worth to consider adding an assert instead of this sub-condition.

Hi Serguei, 
The currentSegmentStart here could be non-zero when  useSegmentHeapDump is false. so we need to check it here. 
Thanks!

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PR: https://git.openjdk.java.net/jdk/pull/4666