On Wed, 13 Apr 2022 15:11:41 GMT, Jaroslav Bachorik <jbacho...@openjdk.org> 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 671: > >> 669: #ifndef ASSERT >> 670: trace->num_frames = ticks_unknown_state; >> 671: AsyncGetCallTraceCallBack cb(trace, depth, ucontext); > > ~Isn't [this > assert](https://github.com/openjdk/jdk/blob/e245f9d2007b0a6c9962b6bf4488ba4d4ce47e92/src/hotspot/os/posix/os_posix.cpp#L1158) > failing? It seems like the crash protection is only for the JFR sampler > thread.~ > > OIC - this is only when asserts are not enabled. I think if we start using ThreadCrashProtection like a general-purpose class, we should make it one and remove the JFR dependencies. ------------- PR: https://git.openjdk.java.net/jdk/pull/8225
