RFR: 8330464: hserr generic events - add entry for the before_exit calls [v2]

[Richard Reingruber]

On Thu, 18 Apr 2024 07:40:23 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> We currently miss a hs_err file generic event entry for before_exit calls. Those would be helpful to see clearly that a crash happened in a shutdown phase (we had this case recently and would have liked to have a hserr event log entry showing this more clearly).
>> 
>> Additionally while testing the event I called System.exit(0)  to check the event.
>> This showed a native backtrace like this 
>> 
>>  Stack: [0x00007f1cfe825000,0x00007f1cfe926000],  sp=0x00007f1cfe924530,  free space=1021k
>> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
>> V  [libjvm.so+0x8fb21b]  before_exit(JavaThread*, bool)+0x4bb  (java.cpp:376)
>> V  [libjvm.so+0x9da27c]  JVM_Halt+0x6c  (jvm.cpp:442)
>> j  java.lang.Shutdown.halt0(I)V+0 java.base at 23.0.0.1-internal
>> j  java.lang.Shutdown.halt(I)V+7 java.base at 23.0.0.1-internal
>> j  java.lang.Shutdown.exit(I)V+16 java.base at 23.0.0.1-internal
>> j  java.lang.Runtime.exit(I)V+14 java.base at 23.0.0.1-internal
>> j  java.lang.System.exit(I)V+4 java.base at 23.0.0.1-internal
>> 
>> So the comment in thread.cpp seems to be outdated, Threads::destroy_vm()  is not in the callstack  and vm_exit() is not seen as well in the callstack so probably the comment needs adjustment.
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   adjust comment in threads.cpp

src/hotspot/share/runtime/threads.cpp line 837:

> 835: // the program falls off the end of main(). Another VM exit path is through
> 836: // vm_exit() when the program calls System.exit() to return a value, or when
> 837: // there is a serious error in VM.

I'm not a native english speaker but I think all elements in the series need to be separated by commas.
Otherwise the misinterpretation that `System.exit()` calls `vm_exit()` is more likely.

Suggestion:

// vm_exit(), when the program calls System.exit() to return a value, or when
// there is a serious error in VM.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18809#discussion_r1570196092