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<manualpage metafile="socache.xml.meta">
<title>Shared Object Cache in Apache HTTP Server</title>
<summary>
<p>The Shared Object Cache provides a means to share simple data
across all a server's workers, regardless of <a href="mpm.html">thread
and process models</a>. It is used where the advantages of sharing
data across processes outweigh the performance overhead of
inter-process communication.</p>
</summary>
<seealso><module>mod_socache_dbm</module></seealso>
<seealso><module>mod_socache_dc</module></seealso>
<seealso><module>mod_socache_memcache</module></seealso>
<seealso><module>mod_socache_shmcb</module></seealso>
<section id="providers">
<title>Shared Object Cache Providers</title>
<p>The shared object cache as such is an abstraction. Four different
modules implement it. To use the cache, one or more of these modules
must be present, and configured.</p>
<p>The only configuration required is to select which cache provider
to use. This is the responsibility of modules using the cache, and
they enable selecton using directives such as
<directive module="authn_socache">AuthnCacheSOCache</directive>,
<directive module="ssl">SSLSessionCache</directive>, and
<directive module="ssl">SSLStaplingCache</directive>.</p>
<p>Currently available providers are:</p>
<dl>
<dt><module>mod_socache_dbm</module> ("dbm")</dt>
<dd>This makes use of a DBM hash file.
The choice of underlying DBM configuration may be configurable
if the installed APR version supports multiple DBM implementations.</dd>
<dt><module>mod_socache_dc</module> ("dc")</dt>
distributed session caching libraries.</dd>
<dt><module>mod_socache_memcache</module> ("mc")</dt>
high-performance, distributed memory object caching system.</dd>
<dt><module>mod_socache_shmcb</module> ("shmcb")</dt>
<dd>This makes use of a high-performance cyclic buffer inside a
shared memory segment.</dd>
</dl>
</section>
</manualpage>