On Tue, 28 Oct 2025 06:22:14 GMT, SendaoYan <[email protected]> wrote:
> Hi all,
>
> We observed the test
> vmTestbase/nsk/jvmti/AttachOnDemand/attach020/TestDescription.java
> intermittent fails. since the target application intermittent OOM. The target
> application will try to exhaust the heap memory and then trigger garbage
> collection by `ClassUnloader.eatMemory()` in file
> test/hotspot/jtreg/vmTestbase/nsk/jvmti/AttachOnDemand/attach020/attach020Target.java.
>
> So I think it's better to limited the max heap usage of target application.
> Before this PR, the physical memory usage is about 30.7GB(this depends the
> total free memory on the test machine), and the jtreg main action take about
> 11 seconds to finish; After this PR, the physical memory usage is about
> 126MB, and the jtreg main action take about 0.7 senonds to finish. I use
> below command to get the usage of physical memory.
>
> Change has been verified locally, test-fix only, no risk.
>
>
> grep VmRSS /proc/`ps -ef | grep -w java | grep vmsqe.aod.AppId | awk '{print
> $2}'`/status
I don't see how your changes are fixing the problem described in the CR. The
target process is exiting with an OOME, which shouldn't happen. The OOME is
thrown and caught by ClassUnloader.eatMemory() and should not escape to the
caller. I think your change is good practice for other reasons, but I don't see
it resolving the failure, which I don't think is understood at this point.
A few other things of note about this test:
The test description does not mention provoking an OOME. It says it provokes a
GC by calling System.gc(), so I'm not sure why it now calls
ClassUnloader.eatMemory().
The test has exclusiveAccess.dirs=. in TEST.properties. This is probably
because of the eatMemory() call and is no longer needed after your heap size
change.
attach021 and attach022 look much like attach020 and could probably use the
same improvements.
I see 6 other tests in nsk/jvmti that call eatMemory() and have
TEST.properties. It seems these could all be improved.
-------------
PR Review: https://git.openjdk.org/jdk/pull/28011#pullrequestreview-3390601550
