RFR: 8289919: [test] LoadLibraryUnloadTest.java failed with "Failed to unload native library" [v4]

[Mandy Chung]

On Fri, 15 Jul 2022 15:31:45 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> The test `java/lang/ClassLoader/loadLibraryUnload/LoadLibraryUnloadTest.java`
>> Fails intermittently when expected output from a subprocess is not found.
>> 
>> I suspect a race between the Cleaner that is going to call JNI_OnUnload (in NativeLibraries.java:377) when the ClassLoader is no longer referenced and the test code that exits as soon as it detects that the p.Class1 is no longer referenced.
>> 
>> The proposed fix is to create a canary object referenced by the native library and released when the library is unloaded.
>> The Java side of the test provides the canary object and uses a WeakReference to wait for it to be released.
>> When released the child process exits and the driver test will find all of the output it expects.
>
> Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add Utils.adjustTimeout to waits for refs to be cleared

Marked as reviewed by mchung (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/9474