On Wed, 13 Jul 2022 14:06:00 GMT, Roger Riggs <rri...@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: > > Cleanup waiting for library unload test/jdk/java/lang/ClassLoader/loadLibraryUnload/libloadLibraryUnload.c line 48: > 46: if (ref == NULL) { > 47: // Only create a single GlobalRef > 48: ref = (*env)->NewGlobalRef(env, obj); Hello Roger, do we not use any synchronization here because even if both winning threads end up concurrently here, the `Object` instance they will be setting as a global ref will be the same one? Ofcourse, there will then be two calls to `NewGlobalRef` for the same instance. I am unaware what the semantics of that call will be in such cases and if it is of any concern. ------------- PR: https://git.openjdk.org/jdk/pull/9474