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8318619: GenShen: Add configurable threshold for young triggers to expedite old evacuations #347

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earthling-amzn
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@earthling-amzn earthling-amzn commented Oct 20, 2023

When Shenandoah expects to free up space by promotions into young, or evacuations in old it may trigger a young collection. This change sets configurable thresholds for these conditions.


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  • JDK-8318619: GenShen: Add configurable threshold for young triggers to expedite old evacuations (Enhancement - P4)

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bridgekeeper bot commented Oct 20, 2023

👋 Welcome back wkemper! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

@openjdk openjdk bot added the rfr Pull request is ready for review label Oct 20, 2023
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mlbridge bot commented Oct 20, 2023

Webrevs

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@kdnilsen kdnilsen left a comment

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Thanks.

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openjdk bot commented Oct 23, 2023

@earthling-amzn This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8318619: GenShen: Add configurable threshold for young triggers to expedite old evacuations

Reviewed-by: kdnilsen

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 2 new commits pushed to the master branch:

  • 5e15c2b: 8318570: GenShen: Only start old cycles if a young cycle is ready to run
  • e6c788e: 8318572: GenShen: Fix error in log message for ingored old-has-grown triggers

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As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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@openjdk openjdk bot added the ready Pull request is ready to be integrated label Oct 23, 2023
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/integrate

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openjdk bot commented Oct 23, 2023

Going to push as commit 0c86364.
Since your change was applied there have been 2 commits pushed to the master branch:

  • 5e15c2b: 8318570: GenShen: Only start old cycles if a young cycle is ready to run
  • e6c788e: 8318572: GenShen: Fix error in log message for ingored old-has-grown triggers

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Oct 23, 2023
@openjdk openjdk bot closed this Oct 23, 2023
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Oct 23, 2023
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openjdk bot commented Oct 23, 2023

@earthling-amzn Pushed as commit 0c86364.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

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@ysramakrishna ysramakrishna left a comment

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LGTM, but left some pretty minor comments.

@@ -144,6 +144,16 @@
" compact - run GC more frequently and with deeper targets to " \
"free up more memory.") \
\
product(uintx, ShenandoahExpeditePromotionsThreshold, 5, EXPERIMENTAL, \
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It's a good idea to add a Percent suffix to this.

"expedite these promotions.") \
range(0,100) \
\
product(uintx, ShenandoahExpediteMixedThreshold, 10, EXPERIMENTAL, \
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Similar to above, may be a good idea to add a Regions suffix to this.

Comment on lines 150 to +152
ShenandoahOldHeuristics* old_heuristics = heap->old_heuristics();
size_t mixed_candidates = old_heuristics->unprocessed_old_collection_candidates();
if (mixed_candidates > 0) {
if (mixed_candidates > ShenandoahExpediteMixedThreshold && !heap->is_concurrent_weak_root_in_progress()) {
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Might be a good idea to move the counting & test of threshold inside the test for collection state.

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