On Wed, 22 Nov 2023 23:58:54 GMT, Jiangli Zhou <jian...@openjdk.org> wrote:
>> Thank you for filing and fixing this issue! I'm kind of late here. Sorry >> for that. >> Is it hard to create a JTreg test for an attaching native thread? I can help >> if you have a standalone prototype. >> You can look for some examples in the folder: >> `test/hotspot/jtreg/serviceability/jvmti/vthread`. > >> Thank you for filing and fixing this issue! I'm kind of late here. Sorry for >> that. Is it hard to create a JTreg test for an attaching native thread? I >> can help if you have a standalone prototype. You can look for some examples >> in the folder: `test/hotspot/jtreg/serviceability/jvmti/vthread`. > > Hi @sspitsyn we don't have an extracted standalone test case (yet) to > demonstrate the crashes. The crashes could not reproduce consistently. > Outside the debugger (lldb), I ran the test (one of the affected ones) 10 > times/per-iteration in order to reproduce. I found the crashes could be > affected by both timing and memory layout. During the investigation, I > noticed the problem became hidden when I increased allocation size for > ThreadsList::_threads (as one of the experiments that I did, I wanted to > mprotect the memory to be read-only in order to find who trashed the memory, > so was trying to allocate memory up to page boundary). That's the reason why > I added noreg-hard tag earlier. > > I gave some more thoughts today. Perhaps, we could write a whitebox test to > check the JvmtiThreadState, without being able to consistently trigger > crashes. We could add a WhiteBox api to iterate the JvmtiThreadState list and > validate if all the JavaThread pointers were valid after detaching. The test > would need to create native threads to attach and detach before the check. > That could more reliably test the 1-1 mapping of JvmtiThreadState and > JavaThread. What do you think? > > Thanks for volunteering to help with the test. I created > https://bugs.openjdk.org/browse/JDK-8320614 today. Should I assign it to you? @jianglizhou Thank you for filing the sub-task. You have already seen some crashes. Even though you do not have a standalone test case, it is still valuable if you describe a test scenario (at least, surfacely) which helped to observe the problem. Could you, add it to the sub-task report, please? ------------- PR Comment: https://git.openjdk.org/jdk/pull/16642#issuecomment-1828977849
