Add logging in Executive.check_running_pid.

third_party/WebKit/Tools/Scripts/webkitpy/common/system/executive.py

 # Copyright (c) 2009, Google Inc. All rights reserved.
 # Copyright (c) 2009 Apple Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
@@ skipping 187 matching lines @@
             if pe32.th32ProcessID == pid:
                 result = True
                 break
             if not Process32Next(hProcessSnap, ctypes.byref(pe32)):
                 break
         CloseHandle(hProcessSnap)
         return result
 
     def check_running_pid(self, pid):
         """Return True if pid is alive, otherwise return False."""
+        _log.debug('Checking whether pid %d is alive.', pid)
         if sys.platform == 'win32':
             return self._win32_check_running_pid(pid)
 
         try:
             os.kill(pid, 0)
             return True
         except OSError:
             return False
 
     def _running_processes(self):
@@ skipping 251 matching lines @@
             pool.close()
             pool.join()
 
 
 def _run_command_thunk(cmd_line_and_cwd):
     # Note that this needs to be a bare module (and hence Picklable) method to work with multiprocessing.Pool.
     (cmd_line, cwd) = cmd_line_and_cwd
     proc = subprocess.Popen(cmd_line, cwd=cwd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     stdout, stderr = proc.communicate()
     return (proc.returncode, stdout, stderr)