Remove decreasing of created connections count when releasing not owned by connection pool connection(fixes issue #2832). (#3514)

* Removing decreasing of created connections count when releasing not owned by connection pool connection(#2832).

* Fixed another issue that was allowing adding connections to a pool owned by other pools. Adding unit tests.

* Fixing a typo in a comment

Author: petyaslavova

redis/connection.py

@@ -1532,18 +1532,18 @@ def release(self, connection: "Connection") -> None:
             except KeyError:
                 # Gracefully fail when a connection is returned to this pool
                 # that the pool doesn't actually own
-                pass
+                return
 
             if self.owns_connection(connection):
                 self._available_connections.append(connection)
                 self._event_dispatcher.dispatch(
                     AfterConnectionReleasedEvent(connection)
                 )
             else:
-                # pool doesn't own this connection. do not add it back
-                # to the pool and decrement the count so that another
-                # connection can take its place if needed
-                self._created_connections -= 1
+                # Pool doesn't own this connection, do not add it back
+                # to the pool.
+                # The created connections count should not be changed,
+                # because the connection was not created by the pool.
                 connection.disconnect()
                 return
 

tests/test_connection_pool.py

@@ -91,6 +91,21 @@ def test_reuse_previously_released_connection(self, master_host):
         c2 = pool.get_connection()
         assert c1 == c2
 
+    def test_release_not_owned_connection(self, master_host):
+        connection_kwargs = {"host": master_host[0], "port": master_host[1]}
+        pool1 = self.get_pool(connection_kwargs=connection_kwargs)
+        c1 = pool1.get_connection("_")
+        pool2 = self.get_pool(
+            connection_kwargs={"host": master_host[0], "port": master_host[1]}
+        )
+        c2 = pool2.get_connection("_")
+        pool2.release(c2)
+
+        assert len(pool2._available_connections) == 1
+
+        pool2.release(c1)
+        assert len(pool2._available_connections) == 1
+
     def test_repr_contains_db_info_tcp(self):
         connection_kwargs = {
             "host": "localhost",

tests/test_multiprocessing.py

@@ -22,16 +22,6 @@ def exit_callback(callback, *args):
 
 
 class TestMultiprocessing:
-    # On macOS and newly non-macOS POSIX systems (since Python 3.14),
-    # the default method has been changed to forkserver.
-    # The code in this module does not work with it,
-    # hence the explicit change to 'fork'
-    # See https://github.com/python/cpython/issues/125714
-    if multiprocessing.get_start_method() in ["forkserver", "spawn"]:
-        _mp_context = multiprocessing.get_context(method="fork")
-    else:
-        _mp_context = multiprocessing.get_context()
-
     # Test connection sharing between forks.
     # See issue #1085 for details.
 
@@ -123,7 +113,7 @@ def target(pool, parent_conn):
                 assert child_conn in pool._available_connections
                 assert parent_conn not in pool._available_connections
 
-        proc = self._mp_context.Process(target=target, args=(pool, parent_conn))
+        proc = multiprocessing.Process(target=target, args=(pool, parent_conn))
         proc.start()
         proc.join(3)
         assert proc.exitcode == 0