Detach engine popen process with parent process

blimp/tools/client_engine_integration.py

 #!/usr/bin/env python
 # Copyright 2016 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.
 
 """Blimp Client + Engine integration test system
 
    Set up Client and Engine
    Set up Forward to connect machine host with client device.
    Start Engine and run blimp on Android Client.
@@ skipping 87 matching lines @@
 
   run_engine_cmd = [
       blimp_engine_app +
       ' --android-fonts-path=' + blimp_fonts_path +
       ' --blimp-client-token-path=' + token_file_path +
       ' --enable-logging=stderr' +
       ' -v=0' +
       ' --vmodule="blimp*=1"']
   p = subprocess.Popen(run_engine_cmd, shell=True,
                        stdout=subprocess.PIPE,
-                       stderr=subprocess.STDOUT)
+                       stderr=subprocess.STDOUT,
+                       preexec_fn=os.setsid)

[shenghuazhang, 2016/08/26 19:47:41]

This shall creates a new process for the popen. Not sure if this could avoid
recipe waiting though.
Couldn't I check it unless commit it into the bot?
'scripts/slave/unittests/recipe_simulation_test.py train' won't verify this I
think.

[jbudorick, 2016/08/26 21:15:06]

No, the simulation test won't verify this. Testing it on an fyi bot is probably
the best way to see if it works.

 
   for line in iter(p.stdout.readline, ''):
     sys.stdout.write(line)
     l = line.rstrip()
     match = re.match(PORT_PATTERN, l)
     if match:
       port = match.group(1)
       break
 
   return port, p
@@ skipping 202 matching lines @@
                else None)
   device = device_utils.DeviceUtils.HealthyDevices(
       blacklist=blacklist, device_arg=serial)[0]
 
   args.func(args, json_file_path, device)
 
 
 if __name__ == '__main__':
   main()