Add more tracing prints to ProcessRead() function.

scripts/common/chromium_utils.py

 # Copyright (c) 2012 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.
 
 """ Set of basic operations/utilities that are used by the build. """
 
 from contextlib import contextmanager
 import ast
 import base64
 import cStringIO
@@ skipping 908 matching lines @@
     """Flush fh every timeout seconds until kill_event is true."""
     while True:
       try:
         fh.flush()
       # File handle is closed, exit.
       except ValueError:
         break
       # Wait for kill signal or timeout.
       if kill_event.wait(timeout):
         break
+    print threading.currentThread(), 'TimedFlush: Finished'
 
   # TODO(all): nsylvain's CommandRunner in buildbot_slave is based on this
   # method.  Update it when changes are introduced here.
   def ProcessRead(readfh, writefh, parser_func=None, filter_obj=None,
                   log_event=None):
     writefh.flush()
 
     # Python on Windows writes the buffer only when it reaches 4k.  Ideally
     # we would flush a minimum of 10 seconds.  However, we only write and
     # flush no more often than 20 seconds to avoid flooding the master with
@@ skipping 21 matching lines @@
 
           if filter_obj:
             filtered_line = filter_obj.FilterLine(in_line.getvalue())
             if filtered_line is not None:
               writefh.write(filtered_line)
           else:
             writefh.write(in_line.getvalue())
           in_line = cStringIO.StringIO()
         in_byte = readfh.read(1)
 
+      print threading.currentThread(), 'ProcessRead: readfh finished.'
+
       if log_event and in_line.getvalue():
         log_event.set()
 
       # Write remaining data and flush on EOF.
       if parser_func:
         parser_func(in_line.getvalue().strip())
 
       if filter_obj:
         if in_line.getvalue():
           filtered_line = filter_obj.FilterDone(in_line.getvalue())
           if filtered_line is not None:
             writefh.write(filtered_line)
       else:
         if in_line.getvalue():
           writefh.write(in_line.getvalue())
     finally:
+      print threading.currentThread(), 'ProcessRead: cleaning up.'
       kill_event.set()
       flush_thread.join()
       writefh.flush()
+      print  threading.currentThread(), 'ProcessRead: finished.'
 
   pipes = pipes or []
 
   command_str = ' '.join(command)
   debug = ('win_chromium_rel_ng' in command_str and
            'layout_test_wrapper' in command_str)
   if debug:
     print 'Logging extra information to debug layout test hang.'
 
   # Print the given command (which should be a list of one or more strings).
@@ skipping 1003 matching lines @@
     return False
   # Matches e.g. "cl_x86 = path/to/clang-cl.exe"
   clang_cl_re = re.compile(
       r'^cl_x\d\d\s+\=\s+(?P<compiler_path>[^ ]+)\s.*$',
       re.VERBOSE)
   for line in open(build_file):
     m = clang_cl_re.match(line)
     if m:
       return 'clang' in m.group('compiler_path')
   return False