The diagnostic port is a special port that uses threads from a dedicated thread pool to process requests submitted via HTTP. It behaves like a typical HTTP port, except that the server uses the diagnostic thread pool instead of the server thread pool.

By maintaining a separate thread pool, this port improves the troubleshooting capability when the server becomes unresponsive. For example, when the server reaches its maximum number of threads, you cannot open the Integration Server Administrator. This prevents you from accessing information that might help you determine why the threads are not available. It also prevents you from freeing up other server resources. Using the threads from the diagnostic thread pool, the diagnostic port enables you to open the Integration Server Administrator.

When you install the Integration Server, it automatically creates the diagnostic port at 9999. If another port is running at 9999, the server will disable the diagnostic port when you start the Integration Server. To enable the diagnostic port, you must edit the port number. For instructions about how to edit port configurations, see Editing a Port. Only one diagnostic port can exist on each Integration Server.