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8338977: Parallel: Improve heap resizing heuristics
This patch refines Parallel's sizing strategy to improve overall memory management and performance.
The young generation layout has been reconfigured from the previous eden-from/to arrangement to a new from/to-eden order. This new layout facilitates young generation resizing, since we perform resizing after a successful young GC when all live objects are located at the beginning of the young generation. Previously, resizing was often inhibited by live objects residing in the middle of the young generation (from-space). The new layout is illustrated in parallelScavengeHeap.hpp.
NumberSeq is now used to track various runtime metrics, such as minor/major GC pause durations, promoted/survived bytes after a young GC, highest old generation usage, etc. This tracking primarily lives in AdaptiveSizePolicy and its subclass PSAdaptiveSizePolicy.
GC overhead checking, which was previously entangled with adaptive resizing logic, has been extracted and is now largely encapsulated in ParallelScavengeHeap::is_gc_overhead_limit_reached.
Performance evaluation
- SPECjvm2008-Compress shows ~8% improvement on Linux/AArch64 and Linux/x64 (restoring the regression reported in JDK-8332485 and JDK-8338689).
- Fixes the surprising behavior when using a non-default (smaller) value of
GCTimeRatiowith Heapothesys/Hyperalloc, as discussed in this thread. - Performance is mostly neutral across other tested benchmarks: DaCapo, SPECjbb2005, SPECjbb2015, SPECjvm2008, and CacheStress. The number of young-gc sometimes goes up a bit and the total heap-size decreases a bit, because promotion-size-to-old-gen goes down with the more effective eden/survivor-space resizing.
PS: I have opportunistically set the obsolete/expired version to ~~25/26~~ 26/27 for now. I will update them accordingly before merging.
Test: tier1-8
Progress
- [ ] Change must be properly reviewed (1 review required, with at least 1 Reviewer)
- [x] Change must not contain extraneous whitespace
- [ ] Change requires CSR request JDK-8356071 to be approved
- [x] Commit message must refer to an issue
Issues
- JDK-8338977: Parallel: Improve heap resizing heuristics (Enhancement - P4)
- JDK-8356071: Parallel: Improve heap resizing heuristics (CSR)
Reviewing
Using git
Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/25000/head:pull/25000
$ git checkout pull/25000
Update a local copy of the PR:
$ git checkout pull/25000
$ git pull https://git.openjdk.org/jdk.git pull/25000/head
Using Skara CLI tools
Checkout this PR locally:
$ git pr checkout 25000
View PR using the GUI difftool:
$ git pr show -t 25000
Using diff file
Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/25000.diff
Using Webrev
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@albertnetymk This change now passes all automated pre-integration checks.
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8338977: Parallel: Improve heap resizing heuristics
Reviewed-by: zgu, gli, iwalulya
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At the time when this comment was updated there had been 55 new commits pushed to the master branch:
- 594c080b2bde81a48ecccda85ac765218fc93856: 8359760: Remove the jdk.jsobject module
- e6ebefaa404daa4160bdc1c5d9c954c040e2c0c2: 8333857: Test sun/security/ssl/SSLSessionImpl/ResumeChecksServer.java failed: Existing session was used
- 38cd860daa9504bbe5add8c2d045d78c75fb7e38: 8363816: Refactor array name creation
- ... and 52 more: https://git.openjdk.org/jdk/compare/7da274ded4a36c6314702b687fcafcda80ae08c4...master
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Thanks for the aliasmap update, looks good.
I think alias sun.gc.policy.boundaryMoved is removed here as it's already redundant, the rest all match with the counter being removed in the change.
There is a case for removing those old e.g. 1.4.1 aliases separately, in a future change.
Do we have other uses of class AdaptiveSizePolicy except for parallelGC?
No. A followup cleanup can be to merge this class into its sole subclass, used by Parallel.
Going to push as commit ad510fb25e47098d136515c355164e5177c5b419.
Since your change was applied there have been 57 commits pushed to the master branch:
- 2292246f8c11f735f50e2046ec6606e89289e9f5: 8350621: Code cache stops scheduling GC
- 03e9ea169b7e45ae3c2ac23b5fe73d39ae57506f: 8358530: Properties#list should warn against non-String values
- 594c080b2bde81a48ecccda85ac765218fc93856: 8359760: Remove the jdk.jsobject module
- ... and 54 more: https://git.openjdk.org/jdk/compare/7da274ded4a36c6314702b687fcafcda80ae08c4...master
Your commit was automatically rebased without conflicts.
@albertnetymk Pushed as commit ad510fb25e47098d136515c355164e5177c5b419.
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