RFR: 8349094: GenShen: Race between control and regulator threads may violate assertions [v14]
William Kemper
wkemper at openjdk.org
Tue Feb 25 22:06:19 UTC 2025
> There are several changes to the operation of Shenandoah's control threads here.
> * The reason for cancellation is now recorded in `ShenandoahHeap::_cancelled_gc` as a `GCCause`, instead of various member variables in the control thread.
> * The cancellation handling is driven entirely by the cancellation cause
> * The graceful shutdown, alloc failure, humongous alloc failure and preemption requested flags are all removed
> * The shutdown sequence is simpler
> * The generational control thread uses a lock to coordinate updates to the requested cause and generation
> * APIs have been simplified to avoid converting between the generation `type` and the actual generation instance
> * The old heuristic, rather than the control thread itself, is now responsible for resuming old generation cycles
> * The control thread doesn't loop on its own (unless the pacer is enabled).
>
> ## Testing
> * jtreg hotspot_gc_shenandoah
> * dacapo, extremem, diluvian, specjbb2015, specjvm2018, heapothesys
William Kemper has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 32 commits:
- Merge tag 'jdk-25+11' into fix-control-regulator-threads
Added tag jdk-25+11 for changeset 0131c1bf
- Address review feedback (better comments, better names)
- Merge remote-tracking branch 'jdk/master' into fix-control-regulator-threads
- Old gen bootstrap cycle must make it to init mark
- Merge remote-tracking branch 'jdk/master' into fix-control-regulator-threads
- Improve message for assertion
- Make shutdown safer for threads requesting (or expecting) gc
- Do not accept requests if control thread is terminating
- Notify waiters when control thread terminates
- Add event for control thread state changes
- ... and 22 more: https://git.openjdk.org/jdk/compare/0131c1bf...d7858deb
-------------
Changes: https://git.openjdk.org/jdk/pull/23475/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23475&range=13
Stats: 927 lines in 18 files changed: 302 ins; 291 del; 334 mod
Patch: https://git.openjdk.org/jdk/pull/23475.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/23475/head:pull/23475
PR: https://git.openjdk.org/jdk/pull/23475
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