2 Replies Latest reply on Dec 6, 2007 9:42 PM by Ron Sigal

    transporterclient not thread-safe for failover

    craig bordelon Newbie

      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@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 @@
      }