Disabled threaded index-pack for known difficult repositories.

BUG=349576
R=mmoss@google.com

Review URL: https://codereview.chromium.org/210063005

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@259164 0039d316-1c4b-4281-b951-d872f2087c98

gclient_scm.py

@@ -255,7 +255,7 @@ class GitWrapper(SCMWrapper):
       quiet = ['--quiet']
     self._UpdateBranchHeads(options, fetch=False)
 
-    cfg = gclient_utils.DefaultIndexPackConfig()
+    cfg = gclient_utils.DefaultIndexPackConfig(self.url)
     fetch_cmd = cfg + ['fetch', self.remote, '--prune']
     self._Run(fetch_cmd + quiet, options, retry=True)
     self._Run(['reset', '--hard', revision] + quiet, options)
@@ -725,7 +725,7 @@ class GitWrapper(SCMWrapper):
       print('')
     template_path = os.path.join(
         os.path.dirname(THIS_FILE_PATH), 'git-templates')
-    cfg = gclient_utils.DefaultIndexPackConfig()
+    cfg = gclient_utils.DefaultIndexPackConfig(self.url)
     clone_cmd = cfg + [
         'clone', '--no-checkout', '--progress', '--template=%s' % template_path]
     if self.cache_dir:
@@ -937,7 +937,7 @@ class GitWrapper(SCMWrapper):
                     '^\\+refs/branch-heads/\\*:.*$']
       self._Run(config_cmd, options)
       if fetch:
-        cfg = gclient_utils.DefaultIndexPackConfig()
+        cfg = gclient_utils.DefaultIndexPackConfig(self.url)
         fetch_cmd =  cfg + ['fetch', self.remote]
         if options.verbose:
           fetch_cmd.append('--verbose')

gclient_utils.py

@@ -30,6 +30,14 @@ RETRY_INITIAL_SLEEP = 0.5
 _WARNINGS = []
 
 
+# These repos are known to cause OOM errors on 32-bit platforms, due the the
+# very large objects they contain.  It is not safe to use threaded index-pack
+# when cloning/fetching them.
+THREADED_INDEX_PACK_BLACKLIST = [
+  'https://chromium.googlesource.com/chromium/reference_builds/chrome_win.git'
+]
+
+
 class Error(Exception):
   """gclient exception class."""
   def __init__(self, msg, *args, **kwargs):
@@ -990,10 +998,13 @@ def DefaultDeltaBaseCacheLimit():
   else:
     return '512m'
 
-def DefaultIndexPackConfig():
+def DefaultIndexPackConfig(url=''):
   """Return reasonable default values for configuring git-index-pack.
 
   Experiments suggest that higher values for pack.threads don't improve
   performance."""
-  return ['-c', 'pack.threads=5', '-c',
-          'core.deltaBaseCacheLimit=%s' % DefaultDeltaBaseCacheLimit()]
+  cache_limit = DefaultDeltaBaseCacheLimit()
+  result = ['-c', 'core.deltaBaseCacheLimit=%s' % cache_limit]
+  if url in THREADED_INDEX_PACK_BLACKLIST:
+    result.extend(['-c', 'pack.threads=1'])
+  return result