7 p.m.
I have a simple messaging client that opens a topic as both a subcriber and publisher,
with a listener on the subscriber. Once I send and receive one message on the topic, the
program hangs when I try to exit. I know that there must be something I am doing wrong
but cannot see it.
Particulars: JBoss AS 4.0.4.GA, JBoss Messaging 1.0.1.CR3, JDK 1.5.0_06
Here is my code:
package jms;
| import java.io.BufferedReader;
| import java.io.InputStreamReader;
| import javax.jms.JMSException;
| import javax.jms.Message;
| import javax.jms.Session;
| import javax.jms.TextMessage;
| import javax.jms.Topic;
| import javax.jms.TopicConnection;
| import javax.jms.TopicConnectionFactory;
| import javax.jms.TopicPublisher;
| import javax.jms.TopicSession;
| import javax.jms.TopicSubscriber;
| import javax.naming.InitialContext;
| public class Echo implements javax.jms.MessageListener {
| private TopicSession sessionPublisher;
| private TopicSession sessionSubscriber;
| private TopicPublisher publisher;
| private TopicSubscriber subscriber;
| private TopicConnection connection;
| public Echo() throws Exception {
| InitialContext jndi = new InitialContext();
| TopicConnectionFactory factory =
(TopicConnectionFactory)jndi.lookup("ConnectionFactory");
| connection = factory.createTopicConnection();
| sessionPublisher = connection.createTopicSession(false,
| Session.AUTO_ACKNOWLEDGE);
| sessionSubscriber = connection.createTopicSession(false,
| Session.AUTO_ACKNOWLEDGE);
| Topic topic = (Topic)jndi.lookup("topic/testTopic");
| publisher = sessionPublisher.createPublisher(topic);
| subscriber = sessionSubscriber.createSubscriber(topic);
| subscriber.setMessageListener(this);
| connection.start();
| }
| public void onMessage(Message message) {
| try {
| TextMessage textMessage = (TextMessage)message;
| String text = textMessage.getText();
| System.out.println("echo: " + text);
| } catch (JMSException e) {
| e.printStackTrace();
| }
| }
| protected void writeMessage(String text) throws JMSException {
| TextMessage message = sessionPublisher.createTextMessage();
| message.setText(text);
| publisher.publish(message);
| }
| public void close() throws JMSException {
| connection.close();
| }
| public static void main(String[] args) throws Exception {
| Echo echo = new Echo();
| BufferedReader commandLine = new java.io.BufferedReader(new
InputStreamReader(System.in));
| boolean looping = true;
| System.out.println("Echo chamber is ready...");
| while (looping) {
| String s = commandLine.readLine();
| if (s.equals("q")) {
| looping = false;
| } else
| echo.writeMessage(s);
| }
| echo.close();
| System.out.println("Good-bye!");
| }
| }
Here is the output for an example run, followed by a thread dump:
java ... jms.Echo
| log4j:WARN No appenders could be found for
logger (org.jboss.remoting.transport.
| socket.SocketClientInvoker).
| log4j:WARN Please initialize the log4j system properly.
| Echo chamber is ready...
| hello
| echo: hello
| q
| Good-bye!
| Full thread dump Java HotSpot(TM) Client VM (1.5.0_06-b05 mixed mode):
|
| "DestroyJavaVM" prio=6 tid=0x00036fa8 nid=0x114c waiting on condition
[0x0000000
| 0..0x0007fae8]
|
| "SocketServerInvokerThread-192.168.0.101-0" prio=6 tid=0x0ae4fc50 nid=0x16ac
run
| nable [0x0b48f000..0x0b48fae8]
| at java.net.SocketInputStream.socketRead0(Native Method)
| at java.net.SocketInputStream.read(Unknown Source)
| at java.io.BufferedInputStream.fill(Unknown Source)
| at java.io.BufferedInputStream.read(Unknown Source)
| - locked <0x02b520b0> (a java.io.BufferedInputStream)
| at java.io.FilterInputStream.read(Unknown Source)
| at org.jboss.serial.io.JBossObjectInputStream.read(JBossObjectInputStrea
| m.java:193)
| at org.jboss.remoting.transport.socket.ServerThread.readVersion(ServerTh
| read.java:497)
| at org.jboss.remoting.transport.socket.ServerThread.processInvocation(Se
| rverThread.java:414)
| at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.j
| ava:534)
| at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.jav
| a:257)
|
| "Timer-0" daemon prio=6 tid=0x0ae4d998 nid=0xda0 in Object.wait()
[0x0b44f000..0
| x0b44fb68]
| at java.lang.Object.wait(Native Method)
| - waiting on <0x030d3ce0> (a java.util.TaskQueue)
| at java.lang.Object.wait(Unknown Source)
| at java.util.TimerThread.mainLoop(Unknown Source)
| - locked <0x030d3ce0> (a java.util.TaskQueue)
| at java.util.TimerThread.run(Unknown Source)
|
| "GC Daemon" daemon prio=2 tid=0x0ac83120 nid=0x1374 in Object.wait()
[0x0af4f000
| ..0x0af4fd68]
| at java.lang.Object.wait(Native Method)
| - waiting on <0x02fe8a08> (a sun.misc.GC$LatencyLock)
| at sun.misc.GC$Daemon.run(Unknown Source)
| - locked <0x02fe8a08> (a sun.misc.GC$LatencyLock)
|
| "RMI RenewClean-[192.168.0.101:1098]" daemon prio=6 tid=0x0ac8a578
nid=0x1174 in
| Object.wait() [0x0af0f000..0x0af0f9e8]
| at java.lang.Object.wait(Native Method)
| - waiting on <0x02fe8a70> (a java.lang.ref.ReferenceQueue$Lock)
| at java.lang.ref.ReferenceQueue.remove(Unknown Source)
| - locked <0x02fe8a70> (a java.lang.ref.ReferenceQueue$Lock)
| at sun.rmi.transport.DGCClient$EndpointEntry$RenewCleanThread.run(Unknow
| n Source)
| at java.lang.Thread.run(Unknown Source)
|
| "Low Memory Detector" daemon prio=6 tid=0x00a92b20 nid=0x1154 runnable
[0x000000
| 00..0x00000000]
|
| "CompilerThread0" daemon prio=10 tid=0x00a91820 nid=0x10bc waiting on
condition
| [0x00000000..0x0abcf84c]
|
| "Signal Dispatcher" daemon prio=10 tid=0x00a90a18 nid=0x10b4 waiting on
conditio
| n [0x00000000..0x00000000]
|
| "Finalizer" daemon prio=8 tid=0x00a87a30 nid=0x11b8 in Object.wait()
[0x0ab4f000
| ..0x0ab4fc68]
| at java.lang.Object.wait(Native Method)
| - waiting on <0x02fc4768> (a java.lang.ref.ReferenceQueue$Lock)
| at java.lang.ref.ReferenceQueue.remove(Unknown Source)
| - locked <0x02fc4768> (a java.lang.ref.ReferenceQueue$Lock)
| at java.lang.ref.ReferenceQueue.remove(Unknown Source)
| at java.lang.ref.Finalizer$FinalizerThread.run(Unknown Source)
|
| "Reference Handler" daemon prio=10 tid=0x00a86598 nid=0x1514 in
Object.wait() [0
| x0ab0f000..0x0ab0fce8]
| at java.lang.Object.wait(Native Method)
| - waiting on <0x02fc47e8> (a java.lang.ref.Reference$Lock)
| at java.lang.Object.wait(Unknown Source)
| at java.lang.ref.Reference$ReferenceHandler.run(Unknown Source)
| - locked <0x02fc47e8> (a java.lang.ref.Reference$Lock)
|
| "VM Thread" prio=10 tid=0x00a823f8 nid=0x1144 runnable
|
| "VM Periodic Task Thread" prio=10 tid=0x00a90958 nid=0xa0c waiting on
condition
I also tried, in the Echo.close() method, to close the various sessions, unset the
listener, and a few other variations to no avail. It appears as if the listener is still
active, even after the connection is closed.
I did try ending the program with System.exit(0), and that worked, but calling
System.exit() should be only a last ditch effort to bring the JVM down, not the normal way
of exiting an application.
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