RFR: 8298377: JfrVframeStream causes deadlocks in ZGC [v2]

Wed Jan 18 12:47:14 UTC 2023

On Wed, 18 Jan 2023 12:40:25 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

> > Question: does the "start_processing()" call ever reach a malloc, directly or indirectly? If so, it is problematic to call from the sampler thread.
> 
> It does allocate a stack iterator with malloc if it really did need to start processing and it was not yet started. So yes. Would you mind explaining why using malloc is problematic?

The problem is that the suspendee can be holding the malloc lock. Please see https://bugs.openjdk.org/browse/JDK-8274298 for an example situation.

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PR: https://git.openjdk.org/jdk/pull/11586