Sun Java System Directory Server Enterprise Edition 6.3 Reference

request-que-backlog

The number of requests waiting to be processed by a thread. Each request received by the server is accepted, then placed in a queue until a thread is available to process it. The queue backlog should always be small, 0 or close to 0. If the queue backlog is large, use the nsslapd-threadnumber attribute to increase the number of threads available in the server.