One of my CLs[1] was failing telemetry_perf_unittests on win7_chromium_rel_ng[2]. The swarming logs[3] show a connection closed error in devtools. This indicates that Chrome crashed but there is no corresponding stack trace. I couldn't reproduce this crash locally, so I created another CL[4] to always dump the stack trace on failure (in _SystemHealthSharedState.DumpStateUponFailure).

It appears that we only collect the minidump and log the stack trace in AppCrashException. InspectorBackend._ConvertExceptionFromInspectorWebsocket converts from devtools exceptions to telemetry exceptions (such as app crash) and if this code fails we don't see a stack trace. kbr@ suggested that we should always collect the minidump and log the stack trace on failure.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/714654
[2] https://build.chromium.org/p/tryserver.chromium.win/builders/win7_chromium_rel_ng/builds/28594
[3] https://chromium-swarm.appspot.com/task?id=3973d8092d12fb10&refresh=10&show_raw=1
    https://chromium-swarm.appspot.com/task?id=3973d80b1eb00e10&refresh=10&show_raw=1
    https://chromium-swarm.appspot.com/task?id=3973d80ba2fd1710&refresh=10&show_raw=1
[4] https://chromium-review.googlesource.com/c/chromium/src/+/742654

Telemetry stack trace:

  Traceback (most recent call last):
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\story_runner.py", line 104, in _RunStoryAndProcessErrorIfNeeded
      state.RunStory(results)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\common\py_trace_event\py_trace_event\trace_event_impl\decorators.py", line 52, in traced_function
      return func(*args, **kwargs)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\page\shared_page_state.py", line 324, in RunStory
      self._current_page.Run(self)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\page\__init__.py", line 118, in Run
      self.RunPageInteractions(action_runner)
    File "e:\b\swarm_slave\w\ir\tools\perf\page_sets\system_health\system_health_story.py", line 108, in RunPageInteractions
      self._Measure(action_runner)
    File "e:\b\swarm_slave\w\ir\tools\perf\page_sets\system_health\system_health_story.py", line 91, in _Measure
      action_runner.MeasureMemory(deterministic_mode=True)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\common\py_trace_event\py_trace_event\trace_event_impl\decorators.py", line 52, in traced_function
      return func(*args, **kwargs)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\actions\action_runner.py", line 161, in MeasureMemory
      dump_id = self.tab.browser.DumpMemory()
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\browser\browser.py", line 350, in DumpMemory
      return self._browser_backend.DumpMemory(timeout=timeout)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\common\py_trace_event\py_trace_event\trace_event_impl\decorators.py", line 52, in traced_function
      return func(*args, **kwargs)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\backends\chrome\chrome_browser_backend.py", line 322, in DumpMemory
      return self.devtools_client.DumpMemory(timeout=timeout)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\backends\chrome_inspector\devtools_client_backend.py", line 414, in DumpMemory
      return self._tracing_backend.DumpMemory(timeout=timeout)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\backends\chrome_inspector\tracing_backend.py", line 214, in DumpMemory
      'request:\n' + traceback.format_exc())
  TracingUnrecoverableException: Exception raised while sending a Tracing.requestMemoryDump request:
  Traceback (most recent call last):
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\backends\chrome_inspector\tracing_backend.py", line 205, in DumpMemory
      response = self._inspector_websocket.SyncRequest(request, timeout)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\backends\chrome_inspector\inspector_websocket.py", line 116, in SyncRequest
      res = self._Receive(timeout)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\telemetry\internal\backends\chrome_inspector\inspector_websocket.py", line 155, in _Receive
      data = self._socket.recv()
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_core.py", line 293, in recv
      opcode, data = self.recv_data()
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_core.py", line 310, in recv_data
      opcode, frame = self.recv_data_frame(control_frame)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_core.py", line 323, in recv_data_frame
      frame = self.recv_frame()
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_core.py", line 357, in recv_frame
      return self.frame_buffer.recv_frame()
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_abnf.py", line 336, in recv_frame
      self.recv_header()
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_abnf.py", line 286, in recv_header
      header = self.recv_strict(2)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_abnf.py", line 371, in recv_strict
      bytes_ = self.recv(min(16384, shortage))
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_core.py", line 427, in _recv
      return recv(self.sock, bufsize)
    File "e:\b\swarm_slave\w\ir\third_party\catapult\telemetry\third_party\websocket-client\websocket\_socket.py", line 80, in recv
      bytes_ = sock.recv(bufsize)
  error: [Errno 10054] An existing connection was forcibly closed by the remote host