[jdk17] RFR: 8269240: java/foreign/stackwalk/TestAsyncStackWalk.java test failed with concurrent GC [v3]

David Holmes dholmes at openjdk.java.net
Fri Jul 16 02:20:16 UTC 2021

On Thu, 15 Jul 2021 15:54:50 GMT, Jorn Vernee <jvernee 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
> Jorn Vernee has updated the pull request incrementally with one additional commit since the last revision:
>   Address David's review comments

Thanks for the updates.

Minor comments below.


src/hotspot/share/prims/universalUpcallHandler.cpp line 62:

> 60:     guarantee(result == JNI_OK, "Could not attach thread for upcall. JNI error code: %d", result);
> 61:     *should_detach = true;
> 62:     thread = Thread::current();

You could use JavaThread::current() here and avoid the later conversions.

src/hotspot/share/prims/universalUpcallHandler.cpp line 138:

> 136:   debug_only(thread->dec_java_call_counter());
> 137: 
> 138:   // Old thread-local info. has been restored. We are not back in native code.

Pre-existing: I think "not" should be "now".


Marked as reviewed by dholmes (Reviewer).

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

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