[jboss-user] [Remoting] - transporterclient not thread-safe for failover

[cbordelo]

the jboss 1.4.1 transporterclient used by multithreaded program was giving strange results on a clustered server when failing over so i found lack of synchronization in the code.

I made these changes and seems to be helping.
changes to TransporterClient.java.
I would like this fixed in the 2.x and 3.x versions (hello developers).
I think i know how to fix the 2.x version of this code too as it has some new stuff but is likewise broken.
(developers send me an email to bord at iscp.telcordia.com if you need it. thx
Craig)

@@ -93,11 +93,12 @@
    /**
     * Disconnects the remoting client
     */
-   private void disconnect()
+   private synchronized void disconnect()
    {
       if(remotingClient != null)
       {
          remotingClient.disconnect();
+        remotingClient = null;
       }
    }

@@ -232,14 +233,18 @@

       do
       {
+        Client rcl = null;
+        synchronized(this) { rcl = remotingClient; }
+         if (rcl == null) throw new CannotConnectException("Client has been dis
connected.");
          try
          {
             failOver = false;
-            response = remotingClient.invoke(request);
+            response = rcl.invoke(request);
          }
          catch(CannotConnectException cnc)
          {
-            failOver = findAlternativeTarget();
+            failOver = findAlternativeTarget(rcl);
+           if (log.isDebugEnabled()) log.error("on CannotConnectException failO
ver is "+failOver+" for "+rcl.getInvoker().getLocator());
             if(!failOver)
             {
                throw cnc;

@@ -264,7 +269,7 @@
     *
     * @return
     */
-   private boolean findAlternativeTarget()
+   private boolean findAlternativeTarget(Client rcl)
    {
       boolean failover = false;

@@ -287,12 +292,19 @@
                      {
                         // finally found server with target handler
                         InvokerLocator newLocator = data.getInvokerLocator();
-                        if(!remotingClient.getInvoker().getLocator().equals(new
Locator))
+                        if(!rcl.getInvoker().getLocator().equals(newLocator))
                         {
                            try
                            {
-                              remotingClient = new Client(newLocator);
-                              remotingClient.connect();
+                             synchronized(this) {
+                                if (rcl == remotingClient) {
+                                   disconnect();
+                                   remotingClient = new Client(newLocator);
+                                }
+                                //otherwise have to assume some other thread
+                                //has meanwhile changed it
+                                //including even disconnecting
+                             }
                               return true;
                            }
                            catch(Exception e)

@@ -300,6 +312,8 @@
                               log.warn("Problem connecting to newly found alter
nate target.", e);
                            }
                         }
+                       else if (log.isDebugEnabled())
+                          log.error(rcl.getInvoker().getLocator()+" == "+newLoc
ator);
                      }
                   }
                }
@@ -333,4 +347,4 @@
    }


View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4108251#4108251

Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4108251