Allow grit to run in parallel with scons by forking child processes

for each grit builder.  This speeds up the build a bit.

Review URL: http://codereview.chromium.org/27118


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10401 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 11 insertions, 4 deletions

diff --git a/tools/grit/grit/scons.py b/tools/grit/grit/scons.py
index 946c72c..9a88216 100644
--- a/tools/grit/grit/scons.py
+++ b/tools/grit/grit/scons.py
@@ -39,6 +39,14 @@ def _SourceToFile(source):
 
 
 def _Builder(target, source, env):
+  # We fork GRIT into a separate process so we can use more processes between
+  # scons and GRIT. This already runs as separate threads, but because of the
+  # python GIL, all these threads have to share the same process.  By using
+  # fork, we can use multiple processes and processors.
+  pid = os.fork()
+  if pid != 0:
+    os.waitpid(pid, 0)
+    return
   from grit import grit_runner
   from grit.tool import build
   options = grit_runner.Options()
@@ -65,6 +73,9 @@ def _Builder(target, source, env):
   builder.scons_targets = [str(t) for t in target]
   builder.Run(options, [])
 
+  # Exit the child process.
+  os._exit(0)
+
 
 def _Emitter(target, source, env):
   '''A SCons emitter for .grd files, which modifies the list of targes to
@@ -111,10 +122,6 @@ def _Emitter(target, source, env):
             if _IsDebugEnabled():
               print "GRIT: Added target %s" % path
 
-  # GRIT is not thread safe so we should only build one grit target at a time. 
-  # We tell scons about this by making a fake side effect target.
-  env.SideEffect('grit_lock', target)
-
   # return target and source lists
   return (target, source)