Merge pull request #108 from ziyanli-amazon/master

Update SQSConnection to avoid race condition

Author: eddy-aws

pom.xml

@@ -6,7 +6,7 @@
 
   <groupId>com.amazonaws</groupId>
   <artifactId>amazon-sqs-java-messaging-lib</artifactId>
-  <version>1.0.8</version>
+  <version>1.0.9</version>
   <packaging>jar</packaging>
   <name>Amazon SQS Java Messaging Library</name>
   <description>The Amazon SQS Java Messaging Library holds the Java Message Service compatible classes, that are used

src/main/java/com/amazon/sqs/javamessaging/SQSConnection.java

@@ -196,7 +196,14 @@ public Session createSession(boolean transacted, int acknowledgeMode) throws JMS
             throw new JMSException("Unrecognized acknowledgeMode. Cannot create Session.");
         }
         synchronized (stateLock) { 
-            checkClosing();
+            if (closing) {
+                /**
+                 * SQSSession's constructor has already started a SQSSessionCallbackScheduler which should be closed
+                 * before leaving sqsSession object.
+                 */
+                sqsSession.close();
+                throw new IllegalStateException("Connection is closed or closing");
+            }
             sessions.add(sqsSession);
 
             /**