From e901d2fd2e9afe7a175231ec30aa4c8781762c23 Mon Sep 17 00:00:00 2001
From: Gary Tully <gtully@apache.org>
Date: Fri, 27 Jan 2012 12:53:09 +0000
Subject: [PATCH] https://issues.apache.org/jira/browse/AMQ-3684 - Potential
 deadlock in vm transport setListener when sender is blocked pending space
 Deal with the case of blocked producer

git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@1236664 13f79535-47bb-0310-9956-ffa450edef68
---
 .../activemq/transport/vm/VMTransport.java       | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/activemq-core/src/main/java/org/apache/activemq/transport/vm/VMTransport.java b/activemq-core/src/main/java/org/apache/activemq/transport/vm/VMTransport.java
index 3e05d4a8d8..1c51205d20 100755
--- a/activemq-core/src/main/java/org/apache/activemq/transport/vm/VMTransport.java
+++ b/activemq-core/src/main/java/org/apache/activemq/transport/vm/VMTransport.java
@@ -226,12 +226,20 @@ public class VMTransport implements Transport, Task {
 
     public void setTransportListener(TransportListener commandListener) {
         try {
-            try {
-                enqueueValve.turnOff();
+            // enqueue can block on blocking queue, preventing turnOff
+            // so avoid in that case: https://issues.apache.org/jira/browse/AMQ-3684
+            if (async && getMessageQueue().remainingCapacity() == 0) {
+                // enqueue blocked or will be
                 this.transportListener = commandListener;
                 wakeup();
-            } finally {
-                enqueueValve.turnOn();
+            } else {
+                try {
+                    enqueueValve.turnOff();
+                    this.transportListener = commandListener;
+                    wakeup();
+                } finally {
+                    enqueueValve.turnOn();
+                }
             }
         } catch (InterruptedException e) {
             throw new RuntimeException(e);