On Thu, 5 May 2022 11:51:47 GMT, Jaroslav Bachorik <jbacho...@openjdk.org> wrote:
>> A gist of the fix is to allow relaxed special handling of code blob lookup >> when done for ASGCT. >> >> Currently, a guarantee will fail when we happen to hit a zombie method which >> is still on stack. While this would indicate a serious error for the normal >> execution flow, in case of ASGCT being in progress when the executing thread >> can be expected at any possible method this is something which may happen >> and we really should not take the profiled JVM down due to it. >> >> <hr> >> Unfortunately, I am not able to create a simple reproducer for the crash >> other that testing in our production where the crash is happening >> sporadically. >> However, thanks to @parttimenerd and his [ASGCT stress >> test](https://github.com/parttimenerd/asgct2-tester.git) the problem can be >> reproduced quite reliably. >> >> <br><br> >> >> _Note: This is a followup PR for #8061_ > > Jaroslav Bachorik has updated the pull request incrementally with one > additional commit since the last revision: > > Make sure the code blob result check is correct Changes requested by dholmes (Reviewer). src/hotspot/share/code/codeCache.cpp line 657: > 655: if (current_thread != NULL && current_thread->in_asgct()) { > 656: // when in ASGCT handler things might get rough and not all > guarantees are held > 657: // if the resolved blob is already a zombie return NULL instead of > crashing on guarantee Suggestion: // If called from ACGT the usual invariants may not apply so if we find // a zombie method just return NULL. src/hotspot/share/runtime/thread.hpp line 647: > 645: #endif // __APPLE__ && AARCH64 > 646: > 647: // support ASGCT Nit: the abbreviation for AsyncGetCallTrace is AGCT not ASGCT src/hotspot/share/runtime/thread.hpp line 649: > 647: // support ASGCT > 648: private: > 649: bool _in_asgct; The position of this field may be significant. See if there are gaps in the Thread structure which this bool might be able to fill. ------------- PR: https://git.openjdk.java.net/jdk/pull/8549
