RFR: JDK-8315478: GenShen: Tolerate round-off errors in preselected promotion budget

[Kelvin Nilsen]

On Fri, 1 Sep 2023 16:33:20 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

> An assert failure identified an error in previous implementation.  See JBS ticket for description of issue and reproducer.

Though all GHA checks have passed, there are still some failures on this branch in internal CI pipelines.  Specifically:

1. perf_specjbb (2 of 5 runs) encountered:

# A fatal error has been detected by the Java Runtime Environment
#  SIGSEGV (0xb) at pc=0x00007fdc7a8f3939, pid=15605, tid=15607
# JRE version: OpenJDK Runtime Environment (22.0) (build 22-root-tolerate-roundoff-with-preselected-promotion-gh-x86.5328a6)
# Java VM: OpenJDK 64-Bit Server VM (22-root-tolerate-roundoff-with-preselected-promotion-gh-x86.5328a6, mixed mode, sharing, compressed oops, compressed class ptrs, shenandoah gc, linux-amd64)
# Problematic frame:
  void ShenandoahScanRemembered<ShenandoahDirectCardMarkRememberedSet>::process_clusters<ShenandoahMarkRefsClosure<(ShenandoahGenerationType)2> >(unsigned long, unsigned long, HeapWordImpl**, ShenandoahMarkRefsClosure<(ShenandoahGenerationType)2>*, bool, unsigned int)+0x289

2. stress_dacapo (5 of 5 runs) encountered:

# A fatal error has been detected by the Java Runtime Environment:
#  Internal Error (/codebuild/output/src4035/src/s3/00/src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp:1276), pid=11604, tid=11612
#  Error: Verify init-mark remembered set violation; clean card should be dirty

We believe the first of these is covered by issue: https://bugs.openjdk.org/browse/JDK-8315560

and the second is covered by issue: https://bugs.openjdk.org/browse/JDK-8315044

I will /integrate now, and address the known failures in separate efforts.

-------------

PR Comment: https://git.openjdk.org/shenandoah/pull/317#issuecomment-1707038212
PR Comment: https://git.openjdk.org/shenandoah/pull/317#issuecomment-1707038938