Workaround a limitation in cygwin with Lock creation.

Workaround a limitation in cygwin with Lock creation.

Reuse a common lock to reduce the number of locks created. Poor cygwin users.

R=dpranke@chromium.org
BUG=
TEST=


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=106494

[Dirk Pranke, 2011-10-19 19:40:45]

http://codereview.chromium.org/8353010/diff/1/gclient_utils.py
File gclient_utils.py (left):

http://codereview.chromium.org/8353010/diff/1/gclient_utils.py#oldcode493
gclient_utils.py:493: self.lock = sys.stdout.lock
so what happens if threading.Lock() fails an exception?

[M-A Ruel, 2011-10-19 19:47:56]

http://codereview.chromium.org/8353010/diff/1/gclient_utils.py
File gclient_utils.py (left):

http://codereview.chromium.org/8353010/diff/1/gclient_utils.py#oldcode493
gclient_utils.py:493: self.lock = sys.stdout.lock
On 2011/10/19 19:40:45, Dirk Pranke wrote:
> so what happens if threading.Lock() fails an exception?

The problem that I started seeing is that while this code was trapping the
exception in threading._allocate_lock(), a Lock() was created somewhere else in
the library and *this one* would also fail randomly. So it's simpler to just
serialize everything. Since the code is designed to lock only on mutation, it's
not a big deal.

[Dirk Pranke, 2011-10-19 21:20:45]

lgtm.

seems like we can remove the single lock on other platforms gives us any
performance improvements ... have you benchmarked this?

[M-A Ruel, 2011-10-20 14:28:55]

On 2011/10/19 21:20:45, Dirk Pranke wrote:
> seems like we can remove the single lock on other platforms gives us any
> performance improvements ... have you benchmarked this?

No but locking is definitely not the biggest performance hit here as it's mostly
bound by the SCM command execution. Also the GIL already all single thread all
python execution. :(

[commit-bot: I haz the power, 2011-10-20 14:29:06]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/maruel@chromium.org/8353010/1

[commit-bot: I haz the power, 2011-10-20 14:34:48]

Change committed as 106494