From: Antoine Pitrou <solipsis@pitrou.net>
Date: Sun, 1 Nov 2009 11:58:22 +0000 (+0000)
Subject: Buffered I/O: optimize lock taking in the common non-contended case.
X-Git-Tag: v2.7a1~175
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e50efaad9f5b17c849ec81eb7c5ae777c887ebb2;p=thirdparty%2FPython%2Fcpython.git

Buffered I/O: optimize lock taking in the common non-contended case.
---

diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 040f3bf9e76d..9aa7d4b8b8c4 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);