8371420: Still sporadic failures of gc/TestAlwaysPreTouchBehavior.java#<gcname> on Linux after JDK-8359104 by MBaesken · Pull Request #28735 · openjdk/jdk

MBaesken · 2025-12-10T08:57:51Z

After JDK-8359104 where getting RSS was improved, we still see sporadic failures of the test gc/TestAlwaysPreTouchBehavior.java# , for different gcs.
E.g. gc/TestAlwaysPreTouchBehavior.java#Epsilon (with -Xlog:os=debug added for more output)

----------System.err:(13/1278)----------
java.lang.RuntimeException: RSS of this process(24465408b) should be bigger than or equal to heap size(268435456b) (available memory: 16295006208). On Linux Kernel < 4.14 RSS can be inaccurate: expected 24465408 > 268435456

Looks like the RSS values we get are somewhat delayed/inaccurate .

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JDK-8371420: Still sporadic failures of gc/TestAlwaysPreTouchBehavior.java#<gcname> on Linux after JDK-8359104 (Bug - P2)(⚠️ The fixVersion in this issue is [26] but the fixVersion in .jcheck/conf is 27, a new backport will be created when this pr is integrated.)

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Albert Mingkun Yang (@albertnetymk - Reviewer) Review applies to bc65db69
Martin Doerr (@TheRealMDoerr - Reviewer)

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bridgekeeper · 2025-12-10T08:59:36Z

👋 Welcome back mbaesken! 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 · 2025-12-10T09:00:06Z

@MBaesken 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:

8371420: Still sporadic failures of gc/TestAlwaysPreTouchBehavior.java#<gcname> on Linux after JDK-8359104

Reviewed-by: mdoerr, ayang

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 140 new commits pushed to the master branch:

b5ac8f8: 8373246: JDK-8351842 broke native debugging on Linux
45642ac: 8373710: Improve jpackage error reporting
14c93b2: 8373537: Migrate "test/jdk/com/sun/net/httpserver/" to null-safe "SimpleSSLContext" methods
... and 137 more: https://git.openjdk.org/jdk/compare/1bbbce75c5e68429c2a32519eb3c36d964dcdf57...master

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openjdk · 2025-12-10T09:01:26Z

@MBaesken The following label will be automatically applied to this pull request:

hotspot-gc

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

mlbridge · 2025-12-10T09:04:42Z

Webrevs

test/hotspot/jtreg/gc/TestAlwaysPreTouchBehavior.java

albertnetymk

Looks reasonable. I wonder if it makes sense to extract the loop-body into a method so that the retrying logic are not intertwined with each attempt.

Additionally, there seems a preexisting issue that the else branch of (available > requiredAvailable) should probably also throw SkippedException?

MBaesken · 2025-12-11T14:17:53Z

Additionally, there seems a preexisting issue that the else branch of (available > requiredAvailable) should probably also throw SkippedException?

Sorry maybe I miss something - where do you want to see such a SkippedException added ?

albertnetymk · 2025-12-16T09:32:22Z

... where do you want to see such a SkippedException added ?

The else branch of if (available > requiredAvailable) { is empty. Shouldn't there be a SkippedException in the else branch?

MBaesken · 2025-12-18T17:01:47Z

... where do you want to see such a SkippedException added ?

The else branch of if (available > requiredAvailable) { is empty. Shouldn't there be a SkippedException in the else branch?

We would continue the for - loop

        // RSS values we get are sometimes somewhat delayed or inaccurate
        for (int iter=0; iter < maxIter; iter++) {

in this case, without a SkippedException. In the original test before this change, we did not throw a SkippedException as well .
On the other hand , if we really run into the else - branch we must have got a small hostAvailableMemory value, so skipping the test might be a good idea because most likely the hostAvailableMemory will not grow in the for loop,

albertnetymk

Some local variables are loop-invariant, e.g. heapSize. I wonder if extracting them out, thus minimizing the loop-body, can make the whole loop more readable. A bit subjective; up to you.

albertnetymk · 2025-12-19T09:35:09Z

test/hotspot/jtreg/gc/TestAlwaysPreTouchBehavior.java

+            if (rss == 0) {
+                throw new SkippedException("cannot get RSS?");
+            }
+            if (available > requiredAvailable) {


I'd suggest inverting the condition to "early-throw" for uninteresting cases, like above.

I agree. Having both skip cases together makes the code better readable and avoids an extra level of curly braces.

Makes sense, I adjusted the coding.

TheRealMDoerr

Thanks!

MBaesken · 2025-12-19T14:26:06Z

Thanks for the reviews !

/integrate

openjdk · 2025-12-19T14:28:06Z

Going to push as commit dca55b4.
Since your change was applied there have been 140 commits pushed to the master branch:

b5ac8f8: 8373246: JDK-8351842 broke native debugging on Linux
45642ac: 8373710: Improve jpackage error reporting
14c93b2: 8373537: Migrate "test/jdk/com/sun/net/httpserver/" to null-safe "SimpleSSLContext" methods
... and 137 more: https://git.openjdk.org/jdk/compare/1bbbce75c5e68429c2a32519eb3c36d964dcdf57...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-12-19T14:28:19Z

@MBaesken Pushed as commit dca55b4.

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

JDK-8371420

9eb1917

openjdk bot changed the title ~~JDK-8371420: Still sporadic failures of gc/TestAlwaysPreTouchBehavior.java#<gcname> on Linux after JDK-8359104~~ 8371420: Still sporadic failures of gc/TestAlwaysPreTouchBehavior.java#<gcname> on Linux after JDK-8359104 Dec 10, 2025

openjdk bot added the hotspot-gc hotspot-gc-dev@openjdk.org label Dec 10, 2025

openjdk bot added the rfr Pull request is ready for review label Dec 10, 2025

TheRealMDoerr reviewed Dec 10, 2025

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test/hotspot/jtreg/gc/TestAlwaysPreTouchBehavior.java Show resolved Hide resolved

test/hotspot/jtreg/gc/TestAlwaysPreTouchBehavior.java Show resolved Hide resolved

Add a comment about RSS values and adjust indentation

5fd2bba

albertnetymk reviewed Dec 10, 2025

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Add SkippedException for too small host memory

bc65db6

albertnetymk approved these changes Dec 19, 2025

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openjdk bot added the ready Pull request is ready to be integrated label Dec 19, 2025

Refactor test a little more

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openjdk bot closed this Dec 19, 2025

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