PING: Check PerfCounter in core image through JSnap

[Yasumasa Suenaga]

Ping: Can I file it to JBS as new issue?

Yasumasa
2016/01/30 23:08 "Yasumasa Suenaga" <yasuenag at gmail.com>:

> Hi all,
>
> I want to check PerfCounter in core image to analyze state of crashed JVM.
> When I use JSnap tool, I encountered NPE on Fedora 23 x86_64.
>
> I checked core image, and I found PerfMemory::_start, _top, etc are set to
> NULL,
> however, PerfMemory::_initialized is set to 1.
>
> PerfMemory::_start is set to NULL in PerfMemory::destroy(), and this
> function
> is called at before aborting VM.
>
> I fixed as below, and it works fine with JSnap:
> -------------------
> diff -r edfc9e2316e3 src/share/vm/runtime/perfMemory.cpp
> --- a/src/share/vm/runtime/perfMemory.cpp       Sun Jan 24 23:20:12 2016
> +0900
> +++ b/src/share/vm/runtime/perfMemory.cpp       Sat Jan 30 22:41:05 2016
> +0900
> @@ -196,12 +196,6 @@
>      //
>      delete_memory_region();
>    }
> -
> -  _start = NULL;
> -  _end = NULL;
> -  _top = NULL;
> -  _prologue = NULL;
> -  _capacity = 0;
>  }
>
>  // allocate an aligned block of memory from the PerfData memory
> -------------------
>
> I found JDK-6224040: enhance jstat to extract counter information from
> core files .
> At least, we can control shared memory through coredump_filter in modern
> Linux kernel.
>
> Should I work this fix in JDK-6224040 ? or another issue ?
> Please cooperate.
>
>
> Thanks,
>
> Yasumasa
>
>
>
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