Activemq死锁的问题

来源：互联网发布：java主流框架编辑：程序博客网时间：2024/05/21 06:14

开发过程中遇到一个activemq死锁的问题，痛苦经历：

应用场景：

后台进程(appserver1)不断产生任务，发送到queue上
前台应用(appservers)请求过来，到queue上获取消息，并根据消息取对应数据

问题：

多线程到同一个queue上直接调用receive，收消息时，会将queue锁住：

服务器端dump出来的信息如下：

ound one Java-level deadlock:
=============================
"tcp:///10.0.72.76:52012":
waiting to lock monitor 0x080ead4c (object 0x952b6950, a java.util.LinkedList),
which is held by "tcp:///10.0.72.76:52010"
"tcp:///10.0.72.76:52010":
waiting to lock monitor 0x080ead8c (object 0x8e7f6620, a org.apache.activemq.broker.region.QueueSubscription),
which is held by "tcp:///10.0.72.76:52012"

在activemq论坛上发现如下内容patch：

在4.1以及之前的版本，需要自己按以下方式修改源代码

Index: activemq-core/src/main/java/org/apache/activemq/ActiveMQSessionExecutor.java
===================================================================
--- activemq-core/src/main/java/org/apache/activemq/ActiveMQSessionExecutor.java   (revision 480716)
+++ activemq-core/src/main/java/org/apache/activemq/ActiveMQSessionExecutor.java   (revision 480717)
@@ -63,8 +63,11 @@

     public void wakeup() {
         if( !dispatchedBySessionPool ) {
-            if( taskRunner!=null ) {
+            if( session.isSessionAsyncDispatch() ) {
                 try {
+                   if( taskRunner == null ) {
+                      taskRunner =session.connection.getSessionTaskRunner().createTaskRunner(this,"ActiveMQ Session: "+session.getSessionId());
+                   }
                     taskRunner.wakeup();
                 } catch (InterruptedException e) {
                     Thread.currentThread().interrupt();
@@ -101,10 +104,8 @@
     synchronized void start() {
         if( !messageQueue.isRunning() ) {
             messageQueue.start();
-            if( session.isSessionAsyncDispatch() || dispatchedBySessionPool ) {
-               taskRunner =session.connection.getSessionTaskRunner().createTaskRunner(this,"ActiveMQ Session: "+session.getSessionId());
-            }
-            wakeup();
+            if( hasUncomsumedMessages() )
+               wakeup();
         }
     }

该问题在4.1.1和4.2中已经解决，不过目前这两个版本都还没有release。用activemq的同学要小心了。