SSL Session Caching
4-10 Oracle HTTP Server powered by Apache Performance Guide
could be reduced, to act as a throttle on the number of concurrent requests on the
server.
SSL Session Caching
The Oracle HTTP server caches a client’s SSL session information by default. With
session caching, only the first connection to the server incurs high latency. For
example, in a simple test to connect and disconnect to an SSL-enabled server, the
elapsed time for 5 connections was 11.4 seconds without SSL session caching. With
SSL session caching enabled, the elapsed time for 5 round trips was 1.9 seconds.
The SSLSessionCacheTimeout directive in httpd.conf determines how long the
server keeps a session alive (the default is 300 seconds). The session information is
kept in a file. You can specify where to keep the session information using the
SSLSessionCache directive; the default location is the
$ORACLE_HOME/Apache/Apache/logs/ directory. The file can be used by
multiple Oracle HTTP Server processes.
The duration of an SSL session is unrelated to the use of HTTP persistent
connections.
Impact of Logging
This section discusses types of logging, log levels, and the performance implications
for using them.

Access Logging

For static page requests, access logging of the default fields results in a 2-3%
performance cost.

HostNameLookups

By default, the HostNameLookups directive is set to off. The server writes the IP
addresses of incoming requests to the log files. When HostNameLookups is set to
on, the server queries the DNS system on the Internet to find the host name
associated with the IP addresses of each request, then writes the host names to the
log.
Performance degraded by about 3% (best case) in Oracle in-house tests with
HostNameLookups set to on. Depending on the server load and the network
connectivity to your DNS server, the performance cost of the DNS lookup could be
high. Unless you really need to have host names in your logs in real time, it is best