py4j-python-socket-in-use.patch

diff --git a/py4j-python/src/py4j/java_gateway.py b/py4j-python/src/py4j/java_gateway.py
index 4d47694..53addec 100644
--- a/py4j-python/src/py4j/java_gateway.py
+++ b/py4j-python/src/py4j/java_gateway.py
@@ -666,6 +666,10 @@ class CallbackServer(Thread):
         self.server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         self.lock = RLock()
         self.is_shutdown = False
+
+        logger.info('Callback Server Starting')
+        self.server_socket.bind(('localhost', self.port))
+
     
     def run(self):
         """Starts listening and accepting connection requests.
@@ -674,13 +678,12 @@ class CallbackServer(Thread):
         is created and started automatically when a :class:`JavaGateway <py4j.java_gateway.JavaGateway>`
         instance is created.
         """
+        with self.lock:
+            self.is_shutdown = False
+
+        self.server_socket.listen(5)
+        logger.info('Socket listening on' + str(self.server_socket.getsockname()))
         try:
-            with self.lock:
-                self.is_shutdown = False
-            logger.info('Callback Server Starting')
-            self.server_socket.bind(('localhost', self.port))
-            self.server_socket.listen(5)
-            logger.info('Socket listening on' + str(self.server_socket.getsockname()))
             while not self.is_shutdown:
                 socket, _ = self.server_socket.accept()
                 input = socket.makefile('r', 0)
@@ -831,4 +834,4 @@ register_output_converter(REFERENCE_TYPE, lambda target_id, gateway_client: Java
 
 if PY4J_SKIP_COLLECTIONS not in os.environ or os.environ[PY4J_SKIP_COLLECTIONS].lower() not in PY4J_TRUE:
     __import__('py4j.java_collections')
-    
\ No newline at end of file
+
diff --git a/py4j-python/src/py4j/tests/java_callback_test.py b/py4j-python/src/py4j/tests/java_callback_test.py
index 77a7fbe..d0159a3 100644
--- a/py4j-python/src/py4j/tests/java_callback_test.py
+++ b/py4j-python/src/py4j/tests/java_callback_test.py
@@ -11,6 +11,7 @@ import logging
 import subprocess
 import time
 import unittest
+import socket
 
 
 def start_example_server():
@@ -209,6 +210,13 @@ class TestPeriodicCleanup(unittest.TestCase):
         except:
             self.assertTrue(True)
         
+class TestSocketInUse(unittest.TestCase):
+
+    def testSocketInUse(self):
+        port = 25334
+        s = socket.socket(socket.AF_INET)
+        s.bind(('localhost', port))
+        self.assertRaises(socket.error, JavaGateway, start_callback_server=True, python_proxy_port=port)
         
 if __name__ == "__main__":
     #import sys;sys.argv = ['', 'Test.testName']