The summary of the problem. Test is intermittently failing because can't get expected field watch event. The test is failing to get event in the 'setfmodw001b' thread with Xcomp only. I verified that frame with the method 'run' of setfmodw001b is compiled when line 118: setfmodw001.setWatch(4); is executed, however the thread is in interp_only mode. The watch events are supported by interpreter only and just ignored by compiled code.
The reason of failure is race beteween setting interp_only mode in line https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/vmTestbase/nsk/jvmti/SetFieldModificationWatch/setfmodw001.java#L75 and calling method call_helper while the method run() https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/vmTestbase/nsk/jvmti/SetFieldModificationWatch/setfmodw001.java#L116 in newly created thread 'setfmodw001b' is invoked. The javaCalls:call are used to invoke methods from hotspot, so it might be rare issues. But still, synchronization might be improved. The void JavaCalls::call_helper(JavaValue* result, const methodHandle& method, JavaCallArguments* args, TRAPS) checks if interp_only mode is set and use 'Method::from_interpreted_entry()' if not. However the interp_only might be set later before compiled method is called (or enter first safe point?). This might happens in safepoint during transition via handshake. So the running thread is in interp_only mode however the run() method is compiled and executed already and never going to be deoptimized. The additional setWatch calls don't try to deptimize method that are already in interp_only mode. BTW, the when JVMCI is enabled and verified adapter exists it is also will be loaded even in interp_only mode set. There is not race here, just ignoring of interp_only mode. I run failing test with Xcomp ~1000 times and tiers1-5. ------------- Commit messages: - fix - f - with jvmci - fix Changes: https://git.openjdk.org/jdk/pull/20587/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20587&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8205957 Stats: 49 lines in 3 files changed: 16 ins; 22 del; 11 mod Patch: https://git.openjdk.org/jdk/pull/20587.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/20587/head:pull/20587 PR: https://git.openjdk.org/jdk/pull/20587
