On Wed, 13 Apr 2022 14:53:54 GMT, Johannes Bechberger <d...@openjdk.java.net> wrote:
> Move the AsyncGetCallTrace method implementation into a separate method and > wrap its call in non-assert compilation mode in `os::ThreadCrashProtection` > like it is done in > [JFR](https://github.com/openjdk/jdk/blob/965ea8d9cd29aee41ba2b1b0b0c67bb67eca22dd/src/hotspot/share/jfr/periodic/sampling/jfrThreadSampler.cpp#L165). > This prevents AsyncGetCallTrace from crashing on segmentation faults (but not > on `guarantee`s). > > If a crash is observed, then the `num_frames` field of the trace is set to > `ticks_unknown_state` (-7) to signal a state that cannot be properly handled. > `ticks_unknown_state` is currently also used for signaling unknown thread > states but this should not be a problem, as the semantic is the same. If > `num_frames` already has an error code then this error code is not changed. > This helps to distinguish between errors in walking threads in Java and > non-Java mode, as `num_frames` is set there before the walking to the > appropriate error code. > > _Thanks for @tstuefe for suggesting this._ src/hotspot/share/prims/forte.cpp line 508: > 506: > 507: > 508: void asyncGetCallTraceImpl(ASGCT_CallTrace *trace, jint depth, void* > ucontext) { make it static? No need to export this. src/hotspot/share/prims/forte.cpp line 669: > 667: JNIEXPORT > 668: void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* > ucontext) { > 669: #ifndef ASSERT Since ThreadCrashProtection uses Thread::current, here I would bail for Thread::current_or_null_safe() == NULL src/hotspot/share/prims/forte.cpp line 674: > 672: os::ThreadCrashProtection crash_protection; > 673: if (!crash_protection.call(cb)) { > 674: if (trace->num_frames < -10 || trace->num_frames >= 0) { Where does this -10 come from? ------------- PR: https://git.openjdk.java.net/jdk/pull/8225
