When a timeout occurs, log a message saying that's what happened.

build/android/devil/utils/reraiser_thread.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Thread and ThreadGroup that reraise exceptions on the main thread."""
 # pylint: disable=W0212
 
 import logging
 import sys
 import threading
@@ skipping 124 matching lines @@
     Reraises exceptions raised by the child threads and supports breaking
     immediately on exceptions raised on the main thread. Unfinished threads'
     stacks will be logged on watchdog timeout.
 
     Args:
       watcher: Watchdog object providing timeout, by default waits forever.
     """
     try:
       self._JoinAll(watcher)
     except TimeoutError:
+      logging.critical('Timed out. Dumping threads.')
       for thread in (t for t in self._threads if t.isAlive()):
         LogThreadStack(thread)
       raise
 
   def GetAllReturnValues(self, watcher=None):
     """Get all return values, joining all threads if necessary.
 
     Args:
       watcher: same as in |JoinAll|. Only used if threads are alive.
     """
     if any([t.isAlive() for t in self._threads]):
       self.JoinAll(watcher)
     return [t.GetReturnValue() for t in self._threads]
 
 
 def RunAsync(funcs, watcher=None):
   """Executes the given functions in parallel and returns their results.
 
   Args:
     funcs: List of functions to perform on their own threads.
     watcher: Watchdog object providing timeout, by default waits forever.
 
   Returns:
     A list of return values in the order of the given functions.
   """
   thread_group = ReraiserThreadGroup(ReraiserThread(f) for f in funcs)
   thread_group.StartAll()
   return thread_group.GetAllReturnValues(watcher=watcher)