PING: Does CollectedHeap::print_on() need Heap_lock?

[Yasumasa Suenaga]

Hi all,

I've sent a question for Heap_lock in Universe::print_*().
Have you read it?

I think we need to lock Heap_lock in it.
Actually, callers of Universe::print_on() seems to be in safepoint.

However, I'm not sure that, so I want to hear about that before
filing to JBS.


Thanks,

Yasumasa


On 2016/04/12 22:56, Yasumasa Suenaga wrote:
> Hi all,
>
> I have a question about Heap_lock in Universe::print_*().
>
> Universe::print_heap_at_SIGBREAK() gets Heap_lock.
> However, HeapInfoDCmd::execute() and Universe::print_on() do not get Heap_lock.
>
> Should we get Heap_lock when we print heap information?
> I guess that we should get this lock for consistency.
>
> --------------------
> diff -r 87215e99d945 src/share/vm/memory/universe.cpp
> --- a/src/share/vm/memory/universe.cpp  Wed Apr 06 23:42:52 2016 +0000
> +++ b/src/share/vm/memory/universe.cpp  Tue Apr 12 22:23:17 2016 +0900
> @@ -1069,6 +1069,7 @@
>  }
>
>  void Universe::print_on(outputStream* st) {
> +  MutexLocker hl(Heap_lock);
>    st->print_cr("Heap");
>    heap()->print_on(st);
>  }
> diff -r 87215e99d945 src/share/vm/services/diagnosticCommand.cpp
> --- a/src/share/vm/services/diagnosticCommand.cpp       Wed Apr 06 23:42:52 2016 +0000
> +++ b/src/share/vm/services/diagnosticCommand.cpp       Tue Apr 12 22:23:17 2016 +0900
> @@ -413,6 +413,7 @@
>  }
>
>  void HeapInfoDCmd::execute(DCmdSource source, TRAPS) {
> +  MutexLocker hl(Heap_lock);
>    Universe::heap()->print_on(output());
>  }
>
> --------------------
>
> If it is correct, I file it to JBS and send review request.
>
>
> Thanks,
>
> Yasumasa
>
>