- adjustments to pool locking test to fail on OSX

- restored conditional locking to pool, for all conditions of max_overflow > -1

1 files changed, 12 insertions, 7 deletions

diff --git a/lib/sqlalchemy/pool.py b/lib/sqlalchemy/pool.py
index 0377708e9..c3a317c3f 100644
--- a/lib/sqlalchemy/pool.py
+++ b/lib/sqlalchemy/pool.py
@@ -470,7 +470,7 @@ class QueuePool(Pool):
         self._overflow = 0 - pool_size
         self._max_overflow = max_overflow
         self._timeout = timeout
-        self._overflow_lock = threading.Lock()
+        self._overflow_lock = self._max_overflow > -1 and threading.Lock() or None
 
     def recreate(self):
         self.log("Pool recreating")
@@ -480,24 +480,29 @@ class QueuePool(Pool):
         try:
             self._pool.put(conn, False)
         except Queue.Full:
-            self._overflow_lock.acquire()
-            try:
+            if self._overflow_lock is None:
                 self._overflow -= 1
-            finally:
-                self._overflow_lock.release()
+            else:
+                self._overflow_lock.acquire()
+                try:
+                    self._overflow -= 1
+                finally:
+                    self._overflow_lock.release()
 
     def do_get(self):
         try:
             return self._pool.get(self._max_overflow > -1 and self._overflow >= self._max_overflow, self._timeout)
         except Queue.Empty:
-            self._overflow_lock.acquire()
+            if self._overflow_lock is not None:
+                self._overflow_lock.acquire()
             try:
                 if self._max_overflow > -1 and self._overflow >= self._max_overflow:
                     raise exceptions.TimeoutError("QueuePool limit of size %d overflow %d reached, connection timed out" % (self.size(), self.overflow()))
                 con = self.create_connection()
                 self._overflow += 1
             finally:
-                self._overflow_lock.release()
+                if self._overflow_lock is not None:
+                    self._overflow_lock.release()
             return con
 
     def dispose(self):