When a keep-alive request is granted the established socket is kept open after each keep-alive response. Note that a keep-alive response is only possible when the response includes a content-length header.

request 1	request 2	request 3	request 4
20 bytes	120 bytes	60 bytes	?? bytes

]]> You cannot rely on the keep-alive feature for any sort of application-level session state maintenance. ]]> You will have to weigh the trade-off between the extra cpu and memory that output buffering takes against the increased effciency of being able to use keep-alive connections for your dynamic pages.