Sun Java System Application Server Enterprise Edition 8.2 Performance Tuning Guide

Connection Pool

Connection queue information shows the number of sessions in the queue, and the average delay before the connection is accepted.

If your system has extra CPU cycles, keep incrementally increasing connection pool settings and monitor performance after each incremental increase. When performance saturates (stops improving), then stop increasing the settings.

Connection pool settings that affect performance are:

Max Pending Count

Max Pending Count specifies the maximum number of pending connections on the listen socket. Adjust Max Pending Count only when there is a heavy load on the system. For low to medium loads, the default will be acceptable.

After observing system behavior, change the value accordingly, otherwise the server will start dropping connections. Connections that time out on a listen socket whose backlog queue is full will fail. If Max Pending Count is close to the limit, increase the maximum connection queue size to avoid dropping connections under heavy load.

Queue Size

Queue Size specifies the number of outstanding (yet to be serviced) connections that the server can have. For heavily loaded systems (with many users) that have limited request processing threads, adjust this setting to a higher value.

Note –

Setting the connection queue size too high can degrade server performance. It was designed to prevent the server from becoming overloaded with connections it cannot handle. If the server is overloaded, increasing the connection queue size will increase the latency of request handling, and the connection queue will fill up again.

Send Buffer Size

Specifies the size (in bytes) of the send buffer used by sockets.

Receive Buffer Size

Specifies the size (in bytes) of the receive buffer used by sockets.

The Send Buffer Size and Receive Buffer Size are the buffer sizes allocated for output and input buffers, respectively. To tune these parameters, increase them methodically and observe the impact on performance. Stop increasing the values when performance saturates (does not increase significantly).