[Android] Switch all subprocess.Popen calls to use a temporary file instead of PIPE.

build/android/pylib/cmd_helper.py

Index: build/android/pylib/cmd_helper.py
diff --git a/build/android/pylib/cmd_helper.py b/build/android/pylib/cmd_helper.py
index 6dcc911d6287c10d80f53bfe2a5fc8883fa21c90..11b06f9a451b6bd6e758cc623032bec140b2cf28 100644
--- a/build/android/pylib/cmd_helper.py
+++ b/build/android/pylib/cmd_helper.py
@@ -6,11 +6,20 @@
 
 import os
 import logging
+import signal
 import subprocess
+import tempfile
 
 import constants
 
 
+def _call(args, stdout=None, stderr=None, shell=None, cwd=None):

[frankf, 2013/04/09 21:14:05]

-> _Call

[craigdh, 2013/04/09 21:25:00]

Done.

+  return subprocess.call(
+      args=args, cwd=cwd, stdout=stdout, stderr=stderr,
+      shell=shell, close_fds=True,
+      preexec_fn=lambda: signal.signal(signal.SIGPIPE, signal.SIG_DFL))
+
+
 def RunCmd(args, cwd=None):
   """Opens a subprocess to execute a program and returns its return value.
 
@@ -24,7 +33,7 @@ def RunCmd(args, cwd=None):
     Return code from the command execution.
   """
   logging.info(str(args) + ' ' + (cwd or ''))
-  return subprocess.call(args, cwd=cwd)
+  return _call(args, cwd=cwd)
 
 
 def GetCmdOutput(args, cwd=None, shell=False):
@@ -59,12 +68,17 @@ def GetCmdStatusAndOutput(args, cwd=None, shell=False):
     The tuple (exit code, output).
   """
   logging.info(str(args) + ' ' + (cwd or ''))
-  p = subprocess.Popen(args=args, cwd=cwd, stdout=subprocess.PIPE,
-                       stderr=subprocess.PIPE, shell=shell)
-  stdout, stderr = p.communicate()
-  exit_code = p.returncode
+  tmpout = tempfile.TemporaryFile(bufsize=0)
+  tmperr = tempfile.TemporaryFile(bufsize=0)
+  exit_code = _call(args, cwd=cwd, stdout=tmpout, stderr=tmperr, shell=shell)
+  tmperr.seek(0)
+  stderr = tmperr.read()
+  tmperr.close()
   if stderr:
     logging.critical(stderr)
+  tmpout.seek(0)
+  stdout = tmpout.read()

[Isaac (away), 2013/04/09 20:53:54]

I think this will have performance cost; possibly significant on some platforms
(which might not just be ubuntu) -- I have reservations about this change.

[frankf, 2013/04/09 21:14:05]

I'm not concerned with performance at this point. This is a temp solution to get
the bots stable until we roll out Python2.7 with possibly backported Python3
subprocess module.

On 2013/04/09 20:53:54, Isaac wrote:

[craigdh, 2013/04/09 21:25:00]

Running it locally I haven't observed any noticeable performance degradation.
The OS should be smart enough to keep it in RAM. Anyway, this is the only
solution I know of to the PIPE buffer issue, a StringIO or something won't work.
Chromite does the same.

+  tmpout.close()
   logging.info(stdout[:4096])  # Truncate output longer than 4k.
   return (exit_code, stdout)