PING: Check PerfCounter in core image through JSnap

[Yasumasa Suenaga]

PING: Can I file this to JBS ?


On 2016/02/14 21:27, Yasumasa Suenaga wrote:
> Ping: What do you think about this issue?
>
> Yasumasa
>
> On 2016/02/08 19:17, Yasumasa Suenaga wrote:
>> Ping: Can I file it to JBS as new issue?
>>
>> Yasumasa
>>
>> 2016/01/30 23:08 "Yasumasa Suenaga" <yasuenag at gmail.com <mailto: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
>>
>>