RFR: 8256658: Shenandoah: Deadlock between nmethod_entry_barrier and concurrent code root evacuator

Fri Nov 20 14:52:03 UTC 2020

On Fri, 20 Nov 2020 14:36:23 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> Nightly tests revealed a deadlock after JDK-8256415.
> 
> The new concurrent code root evacuating/updating task sets up EvacOOM scope on the top level. If OOM occurs and nmethod_entry_barrier holds per-nmethod lock, while concurrent code root evacuating/updating task tries to acquire the exact per-nmethod lock, we deadlock.
> 
> The solution is to move EvacOOM scope under per-nmethod lock.
> 
> Test:
> - [x] hotspot_gc_shenandoah
> - [x] nightly tests

Looks good to me! Thanks!

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Marked as reviewed by rkennke (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1352