On Fri, 24 Sep 2021 13:46:13 GMT, Lin Zang <lz...@openjdk.org> wrote:
>> src/hotspot/share/services/heapDumper.cpp line 751:
>>
>>> 749: static void before_work() {
>>> 750: assert(_lock == NULL, "ParDumpWriter lock must be initialized only
>>> once");
>>> 751: _lock = new (std::nothrow) PaddedMonitor(Mutex::leaf,
>>> "ParallelHProfWriter_lock", Mutex::_safepoint_check_always);
>>
>> If you change these locks to _safepoint_check_always, you have to acquire
>> them without the Mutex::_no_safepoint_check flags so I don't know why you
>> don't get that assert.
>
> I think it may be because this is actually not a JavaThread. So the assert in
> `Mutex::check_no_safepoint_state` would pass.
> Moreover, I have tried to use `PaddedMonitor(Mutex::nosafepoint,
> "ParallelHProfWriter_lock", Mutex::_safepoint_check_never);` here, but the
> slowdebug would report errors as you mentioned in JDK-8274245.
I agree the flag here and at the place of lock acquiring seems problematic. I
will try to see whether I can use `Mutex::_safepoint_check_never` here and get
rid of the assert.
-------------
PR: https://git.openjdk.java.net/jdk/pull/5681
