RFR: 8319048: Monitor deflation unlink phase prolongs time to safepoint [v7]

[Aleksey Shipilev]

On Fri, 17 Nov 2023 12:39:02 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 11 additional commits since the last revision:
>> 
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Move unlink_batch init to proper place
>>  - Add invariant checking
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Fix test after recent test infra renames
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Batch 500
>>  - Pre-final touchups
>>  - Option range and tests
>>  - ... and 1 more: https://git.openjdk.org/jdk/compare/b870256a...09863092
>
> src/hotspot/share/runtime/globals.hpp line 738:
> 
>> 736:   product(intx, MonitorUnlinkBatch, 500, DIAGNOSTIC,                        \
>> 737:           "The maximum number of monitors to unlink in one batch.")         \
>> 738:           constraint(MonitorUnlinkBatchConstraintFunc, AfterErgo)           \
> 
> Could this have a `range(1, max_jint)` as well? 
> Should it mention MonitorDeflationMax? Or does it even need the constrained by MonitorDeflationMax. While it seems useless to have a value greater than MonitorDeflationMax, it does not seem invalid.

Right. We can do the `range` check here, and simplify the constraint function. And actually we don't have to cap at `MonitorDeflationMax`. I am fixing this in newer commits.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16412#discussion_r1398986023