2009/12/26 John Tangney <jo...@industriallogic.com>: > We are still experiencing this problem. > > To summarize: > 1) We are using 6.0.18. > 2) A single Tomcat works fine and joins the cluster. > 3) Two Tomcats on the SAME MACHINE (different ports - duh) but multicasting > to DIFFERENT multicast IPs each join their respective clusters. (yes, two > clusters.) > 4) Two Tomcats on the SAME machine multicasting to the SAME multicast IP and > we get "An operation was attempted on something that is not a socket" when > we launch the second tomcat. > 5) The exact setup works fine on RHEL and Mac OS X > > This is NOT the 6.0.20 regression > (https://issues.apache.org/bugzilla/show_bug.cgi?id=47308) – we're using > 6.0.18. > This is NOT an issue with Windows getting confused by the bind attribute – > it works fine in cases 2 & 3 above. > > Could it be that windows won't allow two apps to multicast to the same > address at the same time? > > Can anyone help with this issue? > > --johnt >
"An operation was tried on something that is not a socket." is the message that corresponds to the WinSock error code WSAENOTSOCK (10038), see here: http://support.microsoft.com/kb/819124 >From TC 6.0.18 source bundle and from JDK sources it can be seen that Line 206 in McastServiceImpl is socket.setInterface(mcastBindAddress); and that results in some setOption(SocketOptions.IP_MULTICAST_IF) call that goes into native code. see java.net.SocketOptions Regarding the listening on the same address/port: With some search I found the following blog entry by Anthony Wong: http://blogs.msdn.com/anthonywong/archive/2005/09/30/475884.aspx that says: [cite] Because multicasting is a one to many communication, there maybe some occasions when you would like multiple UdpClient instances on the same machine to receive data from the same multicast group and port. To do this, you would need to set the SO_REUSEADDR socket option before joining the multicast group. [/cite] The relevant option in java.net.SocketOptions is SocketOption.SO_REUSEADDR and it is settable through DatagramSocket.setReuseAddress(). The JavaDoc for SO_REUSEADDR says that "it is set by default for MulticastSockets", and it is indeed so: you can see in JDK sources that java.net.MulticastSocket class constructor calls setReuseAddress(true). The JavaDoc for setReuseAddress() says that support for this option is system-dependent, and also suggests you to check result of getReuseAddress(), that "will be false if it is not supported". In the list of errors there is WSAEADDRINUSE error (Address already in use). I wondered why it was not used, because it is directly relevant to the SO_REUSEADDR, if that is actually the cause, but I see that that WSAEADDRINUSE is not listed among the codes returned by the setsockopt() socket API function: http://www.sockets.com/winsock.htm#SetSockOpt http://msdn.microsoft.com/en-us/library/ms740476%28VS.85%29.aspx WSAEADDRINUSE error code is returned by the bind() operation. Returning back to the java code of McastServiceImpl.java of tribes TC 6.0.18: http://svn.apache.org/viewvc/tomcat/tc6.0.x/tags/TOMCAT_6_0_18/java/org/apache/catalina/tribes/membership/McastServiceImpl.java?view=markup Current code: http://svn.apache.org/viewvc/tomcat/tc6.0.x/trunk/java/org/apache/catalina/tribes/membership/McastServiceImpl.java?view=markup Locking in McastServiceImpl.setupSocket() 1) I wonder whether "address" is ignored at all, unless "bind" is also set. I mean, in the first lines of the method if (mcastBindAddress != null) { try { log.info("Attempting to bind the multicast socket to "+address+":"+port); socket = new MulticastSocket(new InetSocketAddress(address,port)); why mcastBindAddress is used in the if() condition, and not address. This code was introduced in rev.586228 http://svn.apache.org/viewvc/tomcat/tc6.0.x/tags/TOMCAT_6_0_18/java/org/apache/catalina/tribes/membership/McastServiceImpl.java?r1=586227&r2=586228&; 2) John Tangney, do you see the following one or two INFO messages in Tomcat log: log.info("Attempting to bind the multicast socket to "+address+":"+port); log.info("Binding to multicast address, failed. Binding to port only."); 3) It is possible to create unbound MulticastSocket, by passing a null instead of SocketAddress to its constructor. Maybe the socket.setInterface(mcastBindAddress); call will succeed if we create an unbound socket with "new MulticastSocket(null)", make setInterface() call, and call bind() later. Best regards, Konstantin Kolinko --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
