Apache Module mod_cache_socache

Summary

mod_cache_socache implements a shared object cache (socache) based storage manager formod_cache.

The headers and bodies of cached responses are combined, and stored underneath a single key in the shared object cache. Anumber of implementations of shared object caches are available to choose from.

Multiple content negotiated responses can be stored concurrently, however the caching of partial content is not yet supported by this module.

# Turn on cachingCacheSocache shmcbCacheSocacheMaxSize 102400<Location "/foo">    CacheEnable socache</Location># Fall back to the disk cacheCacheSocache shmcbCacheSocacheMaxSize 102400<Location "/foo">    CacheEnable socache    CacheEnable disk</Location>

Directives

• CacheSocache
• CacheSocacheMaxSize
• CacheSocacheMaxTime
• CacheSocacheMinTime
• CacheSocacheReadSize
• CacheSocacheReadTime

Bugfix checklist

• httpd changelog
• Known issues
• Report a bug

See also

• mod_cache
• mod_cache_disk
• Caching Guide
• Comments

CacheSocacheDirective

TheCacheSocache directive defines the name of the shared object cache implementation to use, followed by optional arguments for that implementation. Anumber of implementations of shared object caches are available to choose from.

CacheSocache shmcb

CacheSocacheMaxSizeDirective

TheCacheSocacheMaxSize directive sets the maximum size, in bytes, for the combined headers and body of a document to be considered for storage in the cache. The larger the headers that are stored alongside the body, the smaller the body may be.

Themod_cache_socache module will only attempt to cache responses that have an explicit content length, or that are small enough to be written in one pass. This is done to allow themod_cache_disk module to have an opportunity to cache responses larger than those cacheable withinmod_cache_socache.

CacheSocacheMaxSize 102400

CacheSocacheMaxTimeDirective

TheCacheSocacheMaxTime directive sets the maximum freshness lifetime, in seconds, for a document to be stored in the cache. This value overrides the freshness lifetime defined for the document by the HTTP protocol.

CacheSocacheMaxTime 86400

CacheSocacheMinTimeDirective

TheCacheSocacheMinTime directive sets the amount of seconds beyond the freshness lifetime of the response that the response should be cached for in the shared object cache. If a response is only stored for its freshness lifetime, there will be no opportunity to revalidate the response to make it fresh again.

CacheSocacheMinTime 600

CacheSocacheReadSizeDirective

TheCacheSocacheReadSize directive sets the minimum amount of data, in bytes, to be read from the backend before the data is sent to the client. The default of zero causes all data read of any size to be passed downstream to the client immediately as it arrives. Setting this to a higher value causes the disk cache to buffer at least this amount before sending the result to the client. This can improve performance when caching content from a slow reverse proxy.

This directive only takes effect when the data is being saved to the cache, as opposed to data being served from the cache.

CacheSocacheReadSize 102400

CacheSocacheReadTimeDirective

TheCacheSocacheReadTime directive sets the minimum amount of elapsed time that should pass before making an attempt to send data downstream to the client. During the time period, data will be buffered before sending the result to the client. This can improve performance when caching content from a reverse proxy.

The default of zero disables this option.

This directive only takes effect when the data is being saved to the cache, as opposed to data being served from the cache. It is recommended that this option be used alongside theCacheSocacheReadSize directive to ensure that the server does not buffer excessively should data arrive faster than expected.

CacheSocacheReadTime 1000