RFR: 8324174: assert(m->is_entered(current)) failed: invariant [v2]

[Tobias Hartmann]

On Tue, 30 Jan 2024 18:09:27 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> When we fail re-allocate scalarized object during deoptimization we unlock all monitors in affected frames and throw OOM exception [JDK-6898462](https://bugs.openjdk.org/browse/JDK-6898462).
>> The unlocking was done in incorrect order starting from outermost monitor which cause this assert when we unlock following nested monitor (the same object) - it sees that it was already unlocked.
>> 
>> The fix is to start unlocking from most nested/inner monitor.
>> I also noticed that we have incorrect order of frames for re-locking during deoptimization. We should start from outermost frame. Inside frame re-locking order is correct - from outermost monitor.
>> 
>> Added regression test with deep nested locks.
>> Ran tier1-5, Xcomp, stress testing.
>
> Vladimir Kozlov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix spacing

test/hotspot/jtreg/compiler/escapeAnalysis/TestNestedRelockAtDeopt.java line 46:

> 44:             }
> 45:         } catch (OutOfMemoryError oom) {
> 46:             arr = null; // Free memory

This isn't guaranteed to free any memory, right? Isn't there a high risk that we are hitting another OOME below at the `new ArrayList<>()`? Is that what [JDK-8325003](https://bugs.openjdk.org/browse/JDK-8325003) is about?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17600#discussion_r1472357585