RFR: 8314225: SIGSEGV in JavaThread::is_lock_owned [v2]

[David Holmes]

On Wed, 1 May 2024 09:49:06 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> src/hotspot/share/runtime/vframeArray.cpp line 100:
>> 
>>> 98: 
>>> 99:           assert(current_thread->is_Java_thread(), "Must be a JavaThread");
>>> 100:           assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*) current_thread, Handle(current_thread, dest->obj())),
>> 
>> This makes me wonder about the assert at line 96 that allows monitor->owner() == nullptr.  If that can happen due to OOM, then we need to check for that here too.
>
> Nit: don't use C-style casts use `JavaThread::cast(thread_current)`  (though this won't be necessary once you change the type of `current_thread`.

We need a RFE to rename `MonitorInfo::_owner` to be `MonitorInfo::_obj` - the current terminology is very confusing!

But yes we need to check `dest->obj()` for null here.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18940#discussion_r1586112864