test_pthread_abort is failing on macOS & flaky on linux

[sbc100]

Its not clear what changed but this test recently started failing more consistently:

https://chromium-review.googlesource.com/c/emscripten-releases/+/3151159
https://ci.chromium.org/ui/p/emscripten-releases/builders/try/mac/b8836587739777488289/overview

======================================================================
FAIL: test_pthread_abort (test_core.wasm0)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 60, in testPartExecutor
    yield
  File "/opt/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 676, in run
    self._callTestMethod(testMethod)
  File "/opt/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 633, in _callTestMethod
    method()
  File "/opt/s/w/ir/k/install/emscripten/tests/common.py", line 188, in decorated
    f(self, *args, **kwargs)
  File "/opt/s/w/ir/k/install/emscripten/tests/test_core.py", line 2361, in test_pthread_abort
    self.do_run_in_out_file_test('pthread/test_pthread_abort.c', assert_returncode=NON_ZERO)
  File "/opt/s/w/ir/k/install/emscripten/tests/common.py", line 1018, in do_run_in_out_file_test
    self._build_and_run(srcfile, expected, **kwargs)
  File "/opt/s/w/ir/k/install/emscripten/tests/common.py", line 1074, in _build_and_run
    self.assertContained(expected_output, js_output)
  File "/opt/s/w/ir/k/install/emscripten/tests/common.py", line 744, in assertContained
    self.fail("Expected to find '%s' in '%s', diff:\n\n%s\n%s" % (
  File "/opt/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 753, in fail
    raise self.failureException(msg)
AssertionError: Expected to find 'onAbort called
' in 'undefined
pthread sent an error! undefined:undefined: abort(undefined) at Error
    at jsStackTrace (eval at importScripts (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:38:16), <anonymous>:2232:19)
    at stackTrace (eval at importScripts (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:38:16), <anonymous>:2249:16)
    at abort (eval at importScripts (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:38:16), <anonymous>:1630:44)
    at _abort (eval at importScripts (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:38:16), <anonymous>:2492:7)
    at <anonymous>:wasm-function[28]:0x909
    at main (<anonymous>:wasm-function[29]:0x911)
    at eval (eval at importScripts (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:38:16), <anonymous>:1700:22)
    at ___call_main (eval at importScripts (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:38:16), <anonymous>:2259:24)
    at <anonymous>:wasm-function[117]:0x4d4b
    at Object.invokeEntryPoint (eval at importScripts (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:38:16), <anonymous>:2227:32)
    at self.onmessage (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:144:48)
    at MessagePort.<anonymous> (/opt/s/w/ir/tmp/t/tmpw4m97k_f/emscripten_test_wasm0_hsj_lnsx/test_pthread_abort.worker.js:24:5)
    at MessagePort.[nodejs.internal.kHybridDispatch] (internal/event_target.js:354:41)
    at MessagePort.exports.emitMessage (internal/per_context/messageport.js:18:26)

[sbc100]

Seeing this flake on linux too: https://logs.chromium.org/logs/emscripten-releases/buildbucket/cr-buildbucket/8828967471954354369/+/steps/Emscripten_testsuite__AddressSanitizer_/0/stdout

======================================================================
FAIL: test_pthread_abort (test_core.asan)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/b/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 60, in testPartExecutor
    yield
  File "/b/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 676, in run
    self._callTestMethod(testMethod)
  File "/b/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 633, in _callTestMethod
    method()
  File "/b/s/w/ir/k/install/emscripten/tests/common.py", line 197, in decorated
    f(self, *args, **kwargs)
  File "/b/s/w/ir/k/install/emscripten/tests/test_core.py", line 2476, in test_pthread_abort
    self.do_run_in_out_file_test('pthread/test_pthread_abort.c', assert_returncode=NON_ZERO)
  File "/b/s/w/ir/k/install/emscripten/tests/common.py", line 1051, in do_run_in_out_file_test
    self._build_and_run(srcfile, expected, **kwargs)
  File "/b/s/w/ir/k/install/emscripten/tests/common.py", line 1107, in _build_and_run
    self.assertContained(expected_output, js_output)
  File "/b/s/w/ir/k/install/emscripten/tests/common.py", line 780, in assertContained
    self.fail("Expected to find '%s' in '%s', diff:\n\n%s\n%s" % (
  File "/b/s/w/ir/cipd_bin_packages/cpython3/lib/python3.8/unittest/case.py", line 753, in fail
    raise self.failureException(msg)
AssertionError: Expected to find 'onAbort called
' in 'Aborted(native code called abort())
worker.js onmessage() captured an uncaught exception: RuntimeError: Aborted(native code called abort())
pthread sent an error! undefined:undefined: Aborted(native code called abort())

/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.js:173
   throw ex;
   ^
Error [RuntimeError]: Aborted(native code called abort())
    at abort (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:1424:10)
    at _abort (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:4809:2)
    at __original_main (<anonymous>:wasm-function[54]:0x13e0)
    at main (<anonymous>:wasm-function[56]:0x13f2)
    at eval (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:1450:20)
    at ___call_main (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:2081:19)
    at _main_thread (<anonymous>:wasm-function[918]:0x2b066)
    at __asan::AsanThread::ThreadStart(unsigned long long) (<anonymous>:wasm-function[315]:0xfbb4)
    at __asan::asan_thread_start(void*) (<anonymous>:wasm-function[358]:0x11f6d)
    at Object.invokeEntryPoint (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:2041:31)
    at self.onmessage (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:139:48)
    at MessagePort.<anonymous> (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:24:5)
    at MessagePort.[nodejs.internal.kHybridDispatch] (internal/event_target.js:354:41)
    at MessagePort.exports.emitMessage (internal/per_context/messageport.js:18:26)
Emitted 'error' event on process instance at:
    at emitUnhandledRejectionOrErr (internal/event_target.js:545:11)
    at MessagePort.[nodejs.internal.kHybridDispatch] (internal/event_target.js:358:9)
    at MessagePort.exports.emitMessage (internal/per_context/messageport.js:18:26)
Thrown at:
    at /b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.js:173:4
    at emit (events.js:315:20)
    at internal/process/execution.js:163:25
', diff:

--- expected
+++ actual
@@ -1,2 +1,31 @@
-onAbort called
+Aborted(native code called abort())
+worker.js onmessage() captured an uncaught exception: RuntimeError: Aborted(native code called abort())
+pthread sent an error! undefined:undefined: Aborted(native code called abort())

+/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.js:173
+   throw ex;
+   ^
+Error [RuntimeError]: Aborted(native code called abort())
+    at abort (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:1424:10)
+    at _abort (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:4809:2)
+    at __original_main (<anonymous>:wasm-function[54]:0x13e0)
+    at main (<anonymous>:wasm-function[56]:0x13f2)
+    at eval (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:1450:20)
+    at ___call_main (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:2081:19)
+    at _main_thread (<anonymous>:wasm-function[918]:0x2b066)
+    at __asan::AsanThread::ThreadStart(unsigned long long) (<anonymous>:wasm-function[315]:0xfbb4)
+    at __asan::asan_thread_start(void*) (<anonymous>:wasm-function[358]:0x11f6d)
+    at Object.invokeEntryPoint (eval at importScripts (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:38:16), <anonymous>:2041:31)
+    at self.onmessage (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:139:48)
+    at MessagePort.<anonymous> (/b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.worker.js:24:5)
+    at MessagePort.[nodejs.internal.kHybridDispatch] (internal/event_target.js:354:41)
+    at MessagePort.exports.emitMessage (internal/per_context/messageport.js:18:26)
+Emitted 'error' event on process instance at:
+    at emitUnhandledRejectionOrErr (internal/event_target.js:545:11)
+    at MessagePort.[nodejs.internal.kHybridDispatch] (internal/event_target.js:358:9)
+    at MessagePort.exports.emitMessage (internal/per_context/messageport.js:18:26)
+Thrown at:
+    at /b/s/w/ir/tmp/t/tmpgev2f0j7/emscripten_test_asan_o9_3f94p/test_pthread_abort.js:173:4
+    at emit (events.js:315:20)
+    at internal/process/execution.js:163:25
+

[sbc100]

Still flaky: https://app.circleci.com/pipelines/github/emscripten-core/emscripten/21125/workflows/71c287b8-d662-4417-b3cf-f2ebf16f6103/jobs/532291

[kleisauke]

Still flaky: https://circleci.com/gh/emscripten-core/emscripten/626723.

This might be a race condition between the onAbort handler call:

emscripten/src/preamble.js

Lines 435 to 439 in aef5d39

	#if expectToReceiveOnModule('onAbort')
	if (Module['onAbort']) {
	Module['onAbort'](what);
	}
	#endif

And when it throws this exception:

emscripten/src/preamble.js

Lines 491 to 494 in aef5d39

	// Throw the error whether or not MODULARIZE is set because abort is used
	// in code paths apart from instantiation where an exception is expected
	// to be thrown when abort is called.
	throw e;

This would be fine on the main runtime thread, but when ENVIRONMENT_IS_PTHREAD is true, the onAbort handler is asynchronous proxied back to the main thread using a postMessage mechanism:

emscripten/src/library_pthread.js

Lines 347 to 356 in aef5d39

	// When running on a pthread, none of the incoming parameters on the module
	// object are present. Proxy known handlers back to the main thread if specified.
	var handlers = [];
	var knownHandlers = [
	#if expectToReceiveOnModule('onExit')
	'onExit',
	#endif
	#if expectToReceiveOnModule('onAbort')
	'onAbort',
	#endif

emscripten/src/worker.js

Lines 160 to 162 in aef5d39

	Module[handler] = function() {
	postMessage({ cmd: 'callHandler', handler, args: [...arguments] });
	}

So, it might be possible that the pthread propagated the uncaught exception back to the main thread before the callHandler command has arrived.