Rewrote is_flaky.py with use of multiprocessinng

tools/flakiness/is_flaky.py

Index: tools/flakiness/is_flaky.py
diff --git a/tools/flakiness/is_flaky.py b/tools/flakiness/is_flaky.py
new file mode 100755
index 0000000000000000000000000000000000000000..8d1c367728d14c567def2f3bd7198942a9bebfe3
--- /dev/null
+++ b/tools/flakiness/is_flaky.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+# Copyright 2014 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.
+
+"""Runs a test repeatedly to measure its flakiness. The return code is non-zero
+if the failure rate is higher than the specified threshold, but is not 100%."""
+
+import argparse
+import multiprocessing.dummy
+import subprocess
+import sys
+import time
+
+def load_options():
+  parser = argparse.ArgumentParser(description=__doc__)
+  parser.add_argument('--retries', default=1000, type=int,
+                      help='Number of test retries to measure flakiness.')
+  parser.add_argument('--threshold', default=0.05, type=float,
+                      help='Minimum flakiness level at which test is '
+                           'considered flaky.')
+  parser.add_argument('--jobs', '-j', type=int, default=1,
+                      help='Number of parallel jobs to run tests.')
+  parser.add_argument('command', nargs='+', help='Command to run test.')
+  return parser.parse_args()
+
+def run_test(job):
+  print 'Starting retry attempt %d out of %d' % (job['index'] + 1,
+                                                 job['retries'])
+  return subprocess.check_call(job['cmd'], stdout=subprocess.PIPE,
+                               stderr=subprocess.STDOUT)
+
+def main():
+  options = load_options()
+  num_passed = num_failed = 0
+  running = []
+
+  pool = multiprocessing.dummy.Pool(processes=options.jobs)
+  args = [{'index': index, 'retries': options.retries, 'cmd': options.command}
+          for index in range(options.retries)]
+  results = pool.map(run_test, args)
+  num_passed = len([retcode for retcode in results if retcode == 0])
+  num_failed = len(results) - num_passed
+
+  if num_passed == 0:
+    flakiness = 0
+  else:
+    flakiness = num_failed / float(len(results))
+
+  print 'Flakiness is %.2f' % flakiness
+  if flakiness > options.threshold:
+    return 1
+  else:
+    return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())