RFR: 8373945: vmTestbase eatMemory/ClassUnloader provoke OOME to force GC and might cause GC in other threads [v11]

[Chris Plummer]

On Tue, 23 Dec 2025 07:32:47 GMT, SendaoYan <syan at openjdk.org> wrote:

>> Hi all,
>> 
>> This PR use `WhiteBox.getWhiteBox().fullGC()` instead of `eatMemory` to grigger full GC. The OOME trigger by `eatMemory` may cause vmTestbase/nsk/monitoring/stress/classload tests intermittent fails when run those tests simultancely on some machines. The WB.fullGC() might be use for same purpose. It also reduce test execution time.
>> 
>> Change has been verified locally by running tests vmTestbase/nsk/monitoring/stress/classload on linux-x64.
>> 
>> Additional testing:
>> 
>> - [x] All jtreg tests by fastdebug build
>
> SendaoYan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update commnets for ClassUnloader

test/hotspot/jtreg/vmTestbase/nsk/share/ClassUnloader.java line 42:

> 40:  * using WhiteBox.fullGC technique.
> 41:  *
> 42:  * <p>The method <code>unloadClass()</code> is provided which call

should be "calls"

test/hotspot/jtreg/vmTestbase/nsk/share/ClassUnloader.java line 238:

> 236:      *
> 237:      * @throws  Failure if exception other than OutOfMemoryError
> 238:      *           is thrown while trigger full GC

should be "triggering"

test/hotspot/jtreg/vmTestbase/nsk/share/ClassUnloader.java line 248:

> 246:         customClassLoader = null;
> 247: 
> 248:         // force class unloading by trigger full GC

should be "triggering"

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

PR Review Comment: https://git.openjdk.org/jdk/pull/28891#discussion_r2644615480
PR Review Comment: https://git.openjdk.org/jdk/pull/28891#discussion_r2644616395
PR Review Comment: https://git.openjdk.org/jdk/pull/28891#discussion_r2644616746