Add error handling and /proc/statm count in multi-process-rss.py.

tools/multi-process-rss.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 # Counts a resident set size (RSS) of multiple processes without double-counts.
 # If they share the same page frame, the page frame is counted only once.
 #
 # Usage:
 # ./multi-process-rss.py <pid>|<pid>r [...]
@@ skipping 24 matching lines @@
 class _NullHandler(logging.Handler):
   def emit(self, record):
     pass
 
 
 _LOGGER = logging.getLogger('multi-process-rss')
 _LOGGER.addHandler(_NullHandler())
 
 
 def _recursive_get_children(pid):
-  children = psutil.Process(pid).get_children()
+  try:
+    children = psutil.Process(pid).get_children()
+  except psutil.error.NoSuchProcess:
+    return []
   descendant = []
   for child in children:
     descendant.append(child.pid)
     descendant.extend(_recursive_get_children(child.pid))
   return descendant
 
 
 def list_pids(argv):
   pids = []
   for arg in argv[1:]:
@@ skipping 15 matching lines @@
   pids = sorted(set(pids), key=pids.index)  # uniq: maybe slow, but simple.
 
   return pids
 
 
 def count_pageframes(pids):
   pageframes = collections.defaultdict(int)
   pagemap_dct = {}
   for pid in pids:
     maps = procfs.ProcMaps.load(pid)
-    pagemap_dct[pid] = procfs.ProcPagemap.load(pid, maps)
+    if not maps:
+      _LOGGER.warning('/proc/%d/maps not found.' % pid)
+      continue
+    pagemap = procfs.ProcPagemap.load(pid, maps)
+    if not pagemap:
+      _LOGGER.warning('/proc/%d/pagemap not found.' % pid)
+      continue
+    pagemap_dct[pid] = pagemap
 
   for pid, pagemap in pagemap_dct.iteritems():
     for vma in pagemap.vma_internals.itervalues():
       for pageframe, number in vma.pageframes.iteritems():
         pageframes[pageframe] += number
 
   return pageframes
 
 
+def count_statm(pids):
+  resident = 0
+  shared = 0
+  private = 0
+
+  for pid in pids:
+    statm = procfs.ProcStatm.load(pid)
+    if not statm:
+      _LOGGER.warning('/proc/%d/statm not found.' % pid)
+      continue
+    resident += statm.resident
+    shared += statm.share
+    private += (statm.resident - statm.share)
+
+  return (resident, shared, private)
+
+
 def main(argv):
   logging_handler = logging.StreamHandler()
   logging_handler.setLevel(logging.WARNING)
   logging_handler.setFormatter(logging.Formatter(
       '%(asctime)s:%(name)s:%(levelname)s:%(message)s'))
 
   _LOGGER.setLevel(logging.WARNING)
   _LOGGER.addHandler(logging_handler)
 
   if sys.platform.startswith('linux'):
     logging.getLogger('procfs').setLevel(logging.WARNING)
     logging.getLogger('procfs').addHandler(logging_handler)
     pids = list_pids(argv)
     pageframes = count_pageframes(pids)
   else:
     _LOGGER.error('%s is not supported.' % sys.platform)
     return 1
 
   # TODO(dmikurube): Classify this total RSS.
   print len(pageframes) * 4096
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))