KeepAliveTimeout
- The number of seconds Apache will wait for a subsequent request before closing the connection. Once a request has been
received, the timeout value specified by the Timeout directive applies
MinSpareServers
- The MinSpareServers directive sets the desired minimum number of idle child server processes. An idle process is one which is
not handling a request. If there are fewer than MinSpareServers idle, then the parent process creates new children at a
maximum rate of 1 per second.
- Turning off this parameter should only be necessary on very busy sites. Setting this parameter to a large number is almost always
a bad idea.
MaxSpareServers
- The MaxSpareServers directive sets the desired maximum number of idle child server processes. An idle process is one which
is not handling a request. If there are more than MaxSpareServers idle, then the parent process will kill off the excess
processes.
- Tuning off this parameter should only be necessary on very busy sites. Setting this parameter to a large number is almost always
a bad idea.
StartServers
- The StartServers directive sets the number of child server processes created on startup. As the number of processes is
dynamically controlled depending on the load, there is usually little reason to adjust this parameter.
MaxClients
- The MaxClients directive sets the limit on the number of simultaneous requests that can be supported; not more than this
number of child server processes will be created. To configure more than 256 clients, you must edit the
HARD_SERVER_LIMIT entry in httpd.h and recompile.
- Any connection attempts over the MaxClients limit will normally be queued, up to a number based on the ListenBacklog
directive. Once a child process is freed at the end of a different request, the connection will then be serviced.
MaxRequestsPerChild
- The MaxRequestsPerChild directive sets the limit on the number of requests that an individual child server process will handle.
After MaxRequestsPerChild requests, the child process will die. If MaxRequestsPerChild is 0, then the process will never
expire.
- Setting MaxRequestsPerChild to a non-zero limit has two beneficial effects:
it limits the amount of memory that process can consume by (accidental) memory leakage;
- by giving processes a finite lifetime, it helps reduce the number of processes when the server load reduces.
ProxyRequests
- This allows or prevents Apache from functioning as a proxy server. Setting ProxyRequests to 'off' does not disable use of the
ProxyPass directive.
CacheRoot
- Sets the name of the directory to contain cache files; this must be writable by the httpd server. (see the User directive).
Setting CacheRoot enables proxy cacheing; without defining a CacheRoot, proxy functionality will be available if
ProxyRequests are set to On, but no cacheing will be available
CacheSize
- Sets the desired space usage of the cache, in KB (1024-byte units). Although usage may grow above this setting, the garbage
collection will delete files until the usage is at or below this setting.
Depending on the expected proxy traffic volume and CacheGcInterval, use a value which is at least 20 to 40 % lower than
the available space.
CacheGcInterval
- Check the cache every <time> hours, and delete files if the space usage is greater than that set by CacheSize. Note that <time>
accepts a float value, you could for example use CacheGcInterval 1.5 to check the cache every 90 minutes. (If unset, no
garbage collection will be performed, and the cache will grow indefinitely.) Note also that the larger the CacheGcInterval,
the more extra space beyond the configured CacheSize will be needed for the cache between garbage collections.
CacheMaxExpire
- Cachable HTTP documents will be retained for at most <time> hours without checking the origin server. Thus documents can
be at most <time> hours out of date. This restriction is enforced even if an expiry date was supplied with the document.
CacheLastModifiedFactor
- If the origin HTTP server did not supply an expiry date for the document, then estimate one using the formula
expiry-period = time-since-last-modification * <factor>
- For example, if the document was last modified 10 hours ago, and <factor> is 0.1, then the expiry period will be set to 10*0.1
= 1 hour.
- If the expiry-period would be longer than that set by CacheMaxExpire, then the latter takes precedence.
CacheDefaultExpire
- If the document is fetched via a protocol that does not support expiry times, then use <time> hours as the expiry time.
CacheMaxExpire does not override this setting.
NoCache
- The NoCache directive specifies a list of words, hosts and/or domains, separated by spaces. HTTP and non-passworded FTP
documents from matched words, hosts or domains are not cached by the proxy server. The proxy module will also attempt to
determine IP addresses of list items which may be hostnames during startup, and cache them for match test as well. Example:
- NoCache joes-garage.com some-host.co.uk bullwinkle.wotsamattau.edu 'bullwinkle.wotsamattau.edu' would also be matched
if referenced by IP address.
- Note that 'wotsamattau' would also be sufficient to match 'wotsamattau.edu'.
- Note also that
disables caching completely.
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