From b3824f6c5d1dd57ae0e823e42d0fdd0cd021dfdd Mon Sep 17 00:00:00 2001
From: "antoine.pitrou" <antoine.pitrou@6015fed2-1504-0410-9fe1-9d1591cc4771>
Date: Sun, 1 Nov 2009 11:58:22 +0000
Subject: [PATCH] Buffered I/O: optimize lock taking in the common
 non-contended case.

git-svn-id: http://svn.python.org/projects/python/trunk@76007 6015fed2-1504-0410-9fe1-9d1591cc4771
---
 Modules/_io/bufferedio.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 040f3bf9e7..9aa7d4b8b8 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -260,9 +260,11 @@ typedef struct {
 
 #ifdef WITH_THREAD
 #define ENTER_BUFFERED(self) \
-    Py_BEGIN_ALLOW_THREADS \
-    PyThread_acquire_lock(self->lock, 1); \
-    Py_END_ALLOW_THREADS
+    if (!PyThread_acquire_lock(self->lock, 0)) { \
+        Py_BEGIN_ALLOW_THREADS \
+        PyThread_acquire_lock(self->lock, 1); \
+        Py_END_ALLOW_THREADS \
+    }
 
 #define LEAVE_BUFFERED(self) \
     PyThread_release_lock(self->lock);
-- 
2.11.4.GIT