[jdk17] RFR: 8269240: java/foreign/stackwalk/TestAsyncStackWalk.java test failed with concurrent GC

Jorn Vernee jvernee at openjdk.java.net
Tue Jul 13 15:01:57 UTC 2021

On Tue, 13 Jul 2021 13:52:18 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> This patch rewrites the prologue and epilogue of panama upcalls, in order to fix the test failure from the title.
>> Previously, we did a call to potentially attach the current thread to the VM, and then afterwards did the same suspend and stack reguard checks that we do on the back-edge of a native downcall. Then, on the back edge of the upcall we did another conditional call to detach the thread.
>> The suspend and reguard checks on the front-edge are incorrect, so I've changed the 2 calls to mimic what is done by JavaCallWrapper instead (with attach and detach included), and removed the old suspend and stack reguard checks.
>> FWIW, this removes the JavaFrameAnchor save/restore MacroAssembler code. This is now written in C++. Also, MacroAssembler code was added to save/restore the result of the upcall around the call on the back-edge, which was previously missing. Since the new code allocates a handle block as well, I've added handling for those oops to frame & OptimizedUpcallBlob.
>> Testing: local running of `jdk_foreign` on Windows and Linux (WSL). Tier 1-3
> src/hotspot/cpu/x86/frame_x86.cpp line 356:
>> 354: }
>> 355: 
>> 356: OptimizedEntryBlob::FrameData* OptimizedEntryBlob::frame_data_for_frame(const frame& frame) const {
> It makes sense to assert that `frame` refers to optimized entry frame (`assert(frame->is_optimized_entry_frame(), "wrong frame");`.

Good idea. Thanks

> src/hotspot/share/runtime/thread.hpp line 1128:
>> 1126: 
>> 1127:  private:
>> 1128:   DEBUG_ONLY(void verify_frame_info();)
> If you declare `verify_frame_info` as returning a `bool` (and just put a `return true;` at the end of `JavaThread::verify_frame_info()`), you can call it as:
> assert(verify_frame_info(), "unexpected frame info");

Thanks for the suggestion. I'd like to keep it the way it is though, so that the assert message contains the `has_last_frame` & `java_call_counter` values. (this was one of the reason I did this refactor as well, since the assert I was hitting out of those 3 didn't contain that info).


PR: https://git.openjdk.java.net/jdk17/pull/149

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