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

[Martin Doerr]

On Wed, 10 Dec 2025 08:57:51 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> After [JDK-8359104](https://bugs.openjdk.org/browse/JDK-8359104) where getting RSS was improved, we still see sporadic failures of the test gc/TestAlwaysPreTouchBehavior.java#<gcname> , 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 .

test/hotspot/jtreg/gc/TestAlwaysPreTouchBehavior.java line 136:

> 134: 
> 135:     public static void main(String [] args) {
> 136:         int maxIter = 20;

A comment would be helpful describing why we run it in a loop. Maybe "RSS values we get are somewhat delayed or inaccurate"?

test/hotspot/jtreg/gc/TestAlwaysPreTouchBehavior.java line 166:

> 164:                 break;
> 165:               }
> 166:             }

Java code should use 4 spaces indentation.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28735#discussion_r2606002728
PR Review Comment: https://git.openjdk.org/jdk/pull/28735#discussion_r2606005559