Tomcat Servlet - TCP Port Already in Use?

Question

My problem is that tomcat/servlet is not releasing its TCP port after my servlet closes the port. Next time a servlet tries to use the port it gets an error "Port already in use". Using netstat I can see the port is still in use. If I stop tomcat and restart it, the port is released. I have not had this sort of problem writing C programs that use sockets.
My setup is Fedora Core 6 with JDK1.5_14 and Tomcat 5.5.26. I know it's not the latest, but sockets and streams have been around for a long time.
Actual implementation uses a trivial javaserver page to instantiate a class to create/accept connection from a client (JApplet). After connection, it starts a thread to receive data. I am using ServerSocket(), InputStreamReader(), and OutputStreamWriter(). On ServerSocket I set ReuseAddress to true.
I have try/catch on all my I/O and use tomcat context log for error and OK messages. Data transfer is perfect. Detect close by client works. In the context log I see close of streams and ServerSocket occur with no exceptions. Then, I manually close the jsp window. No indication of any problems. If I use different port 2nd time (e.g. 50001) it all works perfect. If I use my default (50000) again, servlet gets an error during bind, "Port already in use".
2.5 years with Java. 5 years with Linux and C.
Please advise or refer

Answer 1

rwengr wrote:
My problem is that tomcat/servlet is not releasing its TCP port after my servlet closes the port. Next time a servlet tries to use the port it gets an error "Port already in use". Using netstat I can see the port is still in use. If I stop tomcat and restart it, the port is released. I have not had this sort of problem writing C programs that use sockets.Nice.... Not sure that matters though.
>
My setup is Fedora Core 6 with JDK1.5_14 and Tomcat 5.5.26. I know it's not the latest, but sockets and streams have been around for a long time.
Actual implementation uses a trivial javaserver page to instantiate a class to create/accept connection from a client (JApplet). Bleah! Don't use a JSP for that. Use a servlet at worst. At best use a Servlet to start some other socket manager class which you can/have tested outside the Servlet Container environment.
After connection, it starts a thread to receive data. I am using ServerSocket(), InputStreamReader(), and OutputStreamWriter(). On ServerSocket I set ReuseAddress to true.
I have try/catch on all my I/O and use tomcat context log for error and OK messages. Data transfer is perfect. Detect close by client works. In the context log I see close of streams and ServerSocket occur with no exceptions. Then, I manually close the jsp window. Closing the browser window has no affect on the server.
No indication of any problems. If I use different port 2nd time (e.g. 50001) it all works perfect. If I use my default (50000) again, servlet gets an error during bind, "Port already in use".
2.5 years with Java. 5 years with Linux and C.
Please advise or referShow some code. If you just want some generic advice it would be to close the port, as soon as you don't need it anymore. But you know that. Without any further code I think that is about all that can be said.
P.S. Make the code as small as possible, compilable, but still demonstrating the problem. Also see: [this tutorial as an example...|http://www.javaworld.com/javaworld/jw-12-1996/jw-12-sockets.html?page=1]