[jdk11u-dev] RFR: 8267666: Add option to jcmd GC.heap_dump to use existing file

[Ralf Schmelter]

On Wed, 14 Jul 2021 13:27:25 GMT, Ralf Schmelter <rschmelter at openjdk.org> wrote:

>> Backport of the heap dump enhancement. CSR includes update releases.
>> 
>> Patch did not apply cleanly, I had to resolve/modify
>> src/hotspot/share/services/diagnosticCommand.cpp
>> src/hotspot/share/services/diagnosticCommand.hpp
>> src/hotspot/share/services/heapDumper.cpp
>> src/hotspot/share/services/heapDumper.hpp
>> 
>> Following files do not exist in 11u:
>> src/hotspot/share/services/heapDumperCompression.cpp
>> src/hotspot/share/services/heapDumperCompression.hpp
>> Changes had been made in heapDumper.cpp/heapDumper.hpp
>> 
>> I have built it on linuxx86_64 and verified that the modified test succeeds. Will also run it through SAP's test suite before merging.
>
> To be able to use the -overwrite flag for domain sockets or pipes this would be needed, but overwriting an existing file would work. 
> 
> I had not backported my change to 11, because the diff between 15 and 11 was large and it wasn't a bugfix, so not strictly needed. But if there is interest, it should be possible.

> Hm, together with this change actually https://bugs.openjdk.java.net/browse/JDK-8234510 seems more worthwhile to do. Maybe you want to look into bringing it to JDK11 now, @schmelter-sap? In any case, this backport seems to be good as is and does not need JDK-8234510 as a prerequisite, though its use is limited for the moment.

Yes, it would make sense to downport it now, since we now have an actual use for it.

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PR: https://git.openjdk.java.net/jdk11u-dev/pull/131