RFR: 8273608: Deadlock when jcmd of OnError attaches to itself [v2]

[Coleen Phillimore]

On Tue, 5 Oct 2021 18:14:07 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> My point is that the code to process the `_mutex_array` should be in a `#else` so that we don't build it or use for debug builds. So a debug build uses `owned_locks()` while a release build uses `_mutex_array`.
>
> Sorry if I missed part of the conversation, but why two different implementations? Why not use _mutex_array always? I dislike having different code in debug and release builds.

https://bugs.openjdk.java.net/browse/JDK-8274794 I also think we should have _owned_locks available in product.
I experimented with adding a mutex_array when we create mutex but this requires synchronization on mutex_array, with potentially a mutex, especially if it's a growable array.  Also, we create and delete Mutex so the array would have to allow deletion.  Just making owned_locks available in product would be really nice, so I filed a bug.

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PR: https://git.openjdk.java.net/jdk/pull/5590