8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false #1600

zhengyu123 · 2020-12-03T15:05:33Z

Since Shenandoah GC safepoints are scheduled by control thread, so that, if querying comes from control thread, the answer should be false.

is_at_shenandoah_safepoint() is still not reliable, even after JDK-8253778, we may consider to scratch it.

hotspot_gc_shenandoah x86_64 and x86_32

Progress

Change must not contain extraneous whitespace
Commit message must refer to an issue
Change must be properly reviewed

Issue

JDK-8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false

Reviewers

Aleksey Shipilev (@shipilev - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1600/head:pull/1600
$ git checkout pull/1600

bridgekeeper · 2020-12-03T15:06:27Z

👋 Welcome back zgu! 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 · 2020-12-03T15:07:51Z

@zhengyu123 The following labels will be automatically applied to this pull request:

hotspot-gc
shenandoah

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

mlbridge · 2020-12-03T15:11:02Z

Webrevs

01: Full - Incremental (c394cee)
00: Full (f87cc53)

shipilev

This looks good, consider fixing a few nits below.

shipilev · 2020-12-03T15:18:40Z

src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp

+public:
+  ShenandoahControlThread*   control_thread() const    { return _control_thread;    }
+


Maybe it is easier to friend the class that wants it, instead of exposing the control thread for everyone?

shipilev · 2020-12-03T15:22:33Z

src/hotspot/share/gc/shenandoah/shenandoahUtils.hpp

+    // Shenandoah GC specific safepoints are scheduled by control thread,
+    // so that, querying from control thread can not happen during those
+    // safepoints.


Consider this wording:

// Shenandoah GC specific safepoints are scheduled by control thread. // So if we are enter here from control thread, then we are definitely not // at Shenandoah safepoint, but at something else.

Updated accordingly.

Thanks, Aleksey.

openjdk · 2020-12-03T15:23:31Z

@zhengyu123 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:

8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false

Reviewed-by: shade

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 13 new commits pushed to the master branch:

b170c83: 8257591: Remove suppression of record preview related warnings in java.lang
66a2e70: 8255845: Memory leak in imageFile.cpp
fa58671: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports
129c377: 8257594: C2 compiled checkcast of non-null object triggers endless deoptimization/recompilation cycle
e4497c9: 8256718: Obsolete the long term deprecated and aliased Trace flags
4a267f1: 8244847: Linux/PPC: runtime/CompressedOops/CompressedClassPointers: smallHeapTest fails
b44a329: 8256864: [windows] Improve tracing for mapping errors
ae1eb28: 8257604: JNI_ArgumentPusherVaArg leaks valist
4169d96: 8257143: Enable JVMCI code installation tests on AArch64
a5a034b: 8257617: TestLinkPlatform fails with new Java source version
... and 3 more: https://git.openjdk.java.net/jdk/compare/cc1915b3b320d9729772a81642cf5ca6563094cd...master

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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

shipilev

Looks good.

zhengyu123 · 2020-12-03T18:42:07Z

/integrate

openjdk · 2020-12-03T18:43:06Z

@zhengyu123 Since your change was applied there have been 18 commits pushed to the master branch:

55f5542: 8026976: ECParameters, Point does not match field size
d3f3c32: 8255742: PrintInlining as compiler directive doesn't print virtual calls
6c9482e: 8257561: Some code is not vectorized after 8251925 and 8250607
70517c8: 8257642: CipherByteBufferOverwriteTest copyright issue
e836396: 8257436: [aarch64] Regressions in ArrayCopyUnalignedDst.testByte/testChar for 65-78 bytes when UseSIMDForMemoryOps is on
b170c83: 8257591: Remove suppression of record preview related warnings in java.lang
66a2e70: 8255845: Memory leak in imageFile.cpp
fa58671: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports
129c377: 8257594: C2 compiled checkcast of non-null object triggers endless deoptimization/recompilation cycle
e4497c9: 8256718: Obsolete the long term deprecated and aliased Trace flags
... and 8 more: https://git.openjdk.java.net/jdk/compare/cc1915b3b320d9729772a81642cf5ca6563094cd...master

Your commit was automatically rebased without conflicts.

Pushed as commit e29ee5b.

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

JDK-8257641

f87cc53

openjdk bot added the rfr Pull request is ready for review label Dec 3, 2020

openjdk bot added hotspot-gc hotspot-gc-dev@openjdk.org shenandoah shenandoah-dev@openjdk.org labels Dec 3, 2020

shipilev approved these changes Dec 3, 2020

View reviewed changes

openjdk bot added the ready Pull request is ready to be integrated label Dec 3, 2020

Update

c394cee

shipilev approved these changes Dec 3, 2020

View reviewed changes

openjdk bot closed this Dec 3, 2020

openjdk bot added integrated Pull request has been integrated and removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Dec 3, 2020

zhengyu123 deleted the JDK-8257641-sh-sfpt-ctrl-thread branch December 3, 2020 18:51

8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false #1600

8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false #1600

zhengyu123 commented Dec 3, 2020 •

edited by openjdk bot

bridgekeeper bot commented Dec 3, 2020

openjdk bot commented Dec 3, 2020

mlbridge bot commented Dec 3, 2020 •

edited

shipilev left a comment

shipilev Dec 3, 2020

shipilev Dec 3, 2020

zhengyu123 Dec 3, 2020

openjdk bot commented Dec 3, 2020 •

edited

shipilev left a comment

zhengyu123 commented Dec 3, 2020

openjdk bot commented Dec 3, 2020

		public:
		ShenandoahControlThread* control_thread() const { return _control_thread; }

8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false #1600

8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false #1600

Conversation

zhengyu123 commented Dec 3, 2020 • edited by openjdk bot

Progress

Issue

Reviewers

Download

bridgekeeper bot commented Dec 3, 2020

openjdk bot commented Dec 3, 2020

mlbridge bot commented Dec 3, 2020 • edited

Webrevs

shipilev left a comment

Choose a reason for hiding this comment

shipilev Dec 3, 2020

Choose a reason for hiding this comment

shipilev Dec 3, 2020

Choose a reason for hiding this comment

zhengyu123 Dec 3, 2020

Choose a reason for hiding this comment

openjdk bot commented Dec 3, 2020 • edited

shipilev left a comment

Choose a reason for hiding this comment

zhengyu123 commented Dec 3, 2020

openjdk bot commented Dec 3, 2020

zhengyu123 commented Dec 3, 2020 •

edited by openjdk bot

mlbridge bot commented Dec 3, 2020 •

edited

openjdk bot commented Dec 3, 2020 •

edited