[master] Integrated: Deflate monitors of dead objects before they become unreachable

[Roman Kennke]

On Wed, 17 Nov 2021 21:49:50 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> I've seen occasional failures in G1, where the refinement thread tries to parse a heap region that has dead objects, and would sometimes see an object with a monitor that has already been deflated. And because deflation does not bother to restore the header of dead objects, it would reach to unknown memory and crash.
> 
> The fix is to restore the header of dead objects just before they become unreachable. This can be done in the closures used by WeakProcessor::weak_oops_do(), right before the weak root will be cleared.
> 
> Testing:
>  - [x] tier1
>  - [x] tier2
>  - [x] tier3
>  - [x] tier4

This pull request has now been integrated.

Changeset: 186e1bd7
Author:    Roman Kennke <rkennke at openjdk.org>
URL:       https://git.openjdk.java.net/lilliput/commit/186e1bd7f3d7049070a35f0f4d104dbd37f209d5
Stats:     21 lines in 4 files changed: 21 ins; 0 del; 0 mod

Deflate monitors of dead objects before they become unreachable

Reviewed-by: shade

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PR: https://git.openjdk.java.net/lilliput/pull/28