Add cross-platform resilience to gclient CPU count probe.
BUG=chromium:444597
Review URL: https://codereview.chromium.org/819133003
git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@293549 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/gclient_utils.py b/gclient_utils.py
index 8d4cf3f..96989a9 100644
--- a/gclient_utils.py
+++ b/gclient_utils.py
@@ -1141,15 +1141,32 @@
def NumLocalCpus():
"""Returns the number of processors.
- Python on OSX 10.6 raises a NotImplementedError exception.
+ multiprocessing.cpu_count() is permitted to raise NotImplementedError, and
+ is known to do this on some Windows systems and OSX 10.6. If we can't get the
+ CPU count, we will fall back to '1'.
"""
+ # Surround the entire thing in try/except; no failure here should stop gclient
+ # from working.
try:
- import multiprocessing
- return multiprocessing.cpu_count()
- except: # pylint: disable=W0702
- # Mac OS 10.6 only
- # pylint: disable=E1101
- return int(os.sysconf('SC_NPROCESSORS_ONLN'))
+ # Use multiprocessing to get CPU count. This may raise
+ # NotImplementedError.
+ try:
+ import multiprocessing
+ return multiprocessing.cpu_count()
+ except NotImplementedError: # pylint: disable=W0702
+ # (UNIX) Query 'os.sysconf'.
+ # pylint: disable=E1101
+ if hasattr(os, 'sysconf') and 'SC_NPROCESSORS_ONLN' in os.sysconf_names:
+ return int(os.sysconf('SC_NPROCESSORS_ONLN'))
+
+ # (Windows) Query 'NUMBER_OF_PROCESSORS' environment variable.
+ if 'NUMBER_OF_PROCESSORS' in os.environ:
+ return int(os.environ['NUMBER_OF_PROCESSORS'])
+ except Exception as e:
+ logging.exception("Exception raised while probing CPU count: %s", e)
+
+ logging.debug('Failed to get CPU count. Defaulting to 1.')
+ return 1
def DefaultDeltaBaseCacheLimit():
"""Return a reasonable default for the git config core.deltaBaseCacheLimit.
