Added GLib/DBus workaround to runtest.py under --do-dbus-workaround option.

scripts/slave/runtest.py

Index: scripts/slave/runtest.py
diff --git a/scripts/slave/runtest.py b/scripts/slave/runtest.py
index e5e4bf6f17a0e337a6ee387a515d0c13955719c1..3ff0f6a95ea0b6d870f1fe3c99dcf333b19edd1c 100755
--- a/scripts/slave/runtest.py
+++ b/scripts/slave/runtest.py
@@ -85,6 +85,29 @@ def get_temp_count():
   return len(os.listdir(tempfile.gettempdir()))
 
 
+def _DoDBusWorkaround():

[ghost stip (do not use), 2013/10/25 18:41:27]

can we just call this LaunchDBus()?

[Ken Russell (switch to Gerrit), 2013/10/25 19:07:12]

Sure, done.

+  """Works around a bug in GLib where it performs operations which

[ghost stip (do not use), 2013/10/25 18:41:27]

"""Launches DBus to work around bug in GLib.

Rest of desc.
"""

[Ken Russell (switch to Gerrit), 2013/10/25 19:07:12]

Done.

+  aren't async-signal-safe (in particular, memory allocations) between
+  fork and exec when it spawns subprocesses. This causes threads
+  inside Chrome's browser and utility processes to get stuck, and this
+  harness to hang waiting for those processes, which will never
+  terminate. This doesn't happen on users' machines, because they have
+  an active desktop session and the DBUS_SESSION_BUS_ADDRESS
+  environment variable set, but it does happen on the bots. See Issue
+  309093 for more details."""
+  import platform
+  import subprocess
+  if (platform.uname()[0].lower() == 'linux' and

[ghost stip (do not use), 2013/10/25 18:41:27]

another option is to only call this in main_linux, which is how xvfb is done. I
think the approach here makes more sense.

[Ken Russell (switch to Gerrit), 2013/10/25 19:07:12]

I like having this here because it should be done as early as possible and makes
the control flow easier to read.

+      'DBUS_SESSION_BUS_ADDRESS' not in os.environ):
+    try:
+      dbus_output = subprocess.check_output(['dbus-launch']).split('\n')

[ghost stip (do not use), 2013/10/25 18:41:27]

put a message here: 'DBUS_SESSION_BUS_ADDRESS not found, starting dbus-launch'

[ghost stip (do not use), 2013/10/25 18:41:27]

I'm assuming dbus-launch daemonizes here, otherwise it will cause the build to
hang at the end. is there an option to dbus-launch to ensure it's daemonized?

[Ken Russell (switch to Gerrit), 2013/10/25 19:07:12]

dbus-launch is synchronous. It runs and exits without starting sub-processes as
far as we have seen (we're already running this workaround for a subset of the
tests on the GPU bots).

[Ken Russell (switch to Gerrit), 2013/10/25 19:07:12]

Done.

+      for line in dbus_output:
+        m = re.match(r"([^=]+)\=(.+)", line)
+        if m:
+          os.environ[m.group(1)] = m.group(2)

[ghost stip (do not use), 2013/10/25 18:41:27]

output to stdout 'setting %s to %s' % (m.group(1), m.group(2))

[Ken Russell (switch to Gerrit), 2013/10/25 19:07:12]

Thanks, I had this before but took it out. Done.

+    except:  # pylint: disable=W0702
+      pass

[ghost stip (do not use), 2013/10/25 18:41:27]

what exception are you expecting here? if it's that dbus-launch isn't found, I
feel like we should print an info message.

[Ken Russell (switch to Gerrit), 2013/10/25 19:07:12]

subprocess.check_output raises CalledProcessError but I wanted to be
conservative in the exceptions caught. Changed to catch everything and print out
any exception that occurs.

[Ken Russell (switch to Gerrit), 2013/10/25 19:12:16]

Sorry, I lied, and made this catch subprocess.CalledProcessError explicitly.

+
 def _RunGTestCommand(command, results_tracker=None, pipes=None,
                      extra_env=None):
 
@@ -1217,6 +1240,10 @@ def main():
                                 'properties "lsan" and "lsan_run_all_tests".')
   option_parser.add_option('', '--extra-sharding-args', default='',
                            help='Extra options for run_test_cases.py.')
+  option_parser.add_option('--do-dbus-workaround', action='store_true',

[ghost stip (do not use), 2013/10/25 18:41:27]

--spawn-dbus

+                           default=False,
+                           help='Work around GLib DBus bug by '
+                                'manually spawning dbus-launch')
 
   chromium_utils.AddPropertiesOptions(option_parser)
   options, args = option_parser.parse_args()
@@ -1234,6 +1261,9 @@ def main():
   # Print out builder name for log_parser
   print '[Running on builder: "%s"]' % options.builder_name
 
+  if options.do_dbus_workaround:
+    _DoDBusWorkaround()
+
   # TODO(thakis): Simplify this once ConvertBuildDirToLegacy() ignores its
   # arguments.
   use_out = False