github.com/krum110487/go-htaccess@v0.0.0-20240316004156-60641c8e7598/tests/data/apache_2_2_34/manual/mod/mod_mem_cache.html.en (about) 1 <?xml version="1.0" encoding="ISO-8859-1"?> 2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 3 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> 4 <meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type" /> 5 <!-- 6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 7 This file is generated from xml source: DO NOT EDIT 8 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 9 --> 10 <title>mod_mem_cache - Apache HTTP Server Version 2.2</title> 11 <link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> 12 <link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> 13 <link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="../style/css/prettify.css" /> 14 <script src="../style/scripts/prettify.min.js" type="text/javascript"> 15 </script> 16 17 <link href="../images/favicon.ico" rel="shortcut icon" /><link href="http://httpd.apache.org/docs/current/mod/mod_mem_cache.html" rel="canonical" /></head> 18 <body> 19 <div id="page-header"> 20 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p> 21 <p class="apache">Apache HTTP Server Version 2.2</p> 22 <img alt="" src="../images/feather.gif" /></div> 23 <div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div> 24 <div id="path"> 25 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.2</a> > <a href="./">Modules</a></div> 26 <div id="page-content"> 27 <div class="retired"><h4>Please note</h4> 28 <p> This document refers to a legacy release (<strong>2.2</strong>) of Apache httpd. The active release (<strong>2.4</strong>) is documented <a href="http://httpd.apache.org/docs/current">here</a>. If you have not already upgraded, please follow <a href="http://httpd.apache.org/docs/current/upgrading.html">this link</a> for more information.</p> 29 <p>You may follow <a href="http://httpd.apache.org/docs/current/mod/mod_mem_cache.html">this link</a> to go to the current version of this document.</p></div><div id="preamble"><h1>Apache Module mod_mem_cache</h1> 30 <div class="toplang"> 31 <p><span>Available Languages: </span><a href="../en/mod/mod_mem_cache.html" title="English"> en </a> | 32 <a href="../ja/mod/mod_mem_cache.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 33 <a href="../ko/mod/mod_mem_cache.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p> 34 </div> 35 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Content cache keyed to URIs</td></tr> 36 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr> 37 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>mem_cache_module</td></tr> 38 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_mem_cache.c</td></tr></table> 39 <h3>Summary</h3> 40 41 <p>This module <em>requires</em> the service of <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code>. It acts as a support module for <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> and provides a memory based storage manager. 42 <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> can be configured to operate in two 43 modes: caching open file descriptors or caching objects in heap storage. 44 <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> is most useful when used to cache locally 45 generated content or to cache backend server content for <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> configured for <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code> (aka <dfn>reverse proxy</dfn>).</p> 46 47 <p>Content is stored in and retrieved from the cache using URI based 48 keys. Content with access protection is not cached.</p> 49 50 <div class="note"><h3>Note</h3>In most cases <code class="module"><a href="../mod/mod_disk_cache.html">mod_disk_cache</a></code> 51 should be the preferred choice. This is explained further in the <a href="../caching.html#inmemory">Caching Guide</a>. In particular, 52 this module's cache is <em>per-process</em>, which can be partially 53 mitigated by configuring threaded MPMs to use fewer child processes 54 via configuration of larger values for <code class="directive"><a href="../mod/mpm_common.html#threadsperchild">ThreadsPerChild</a></code>. This module's cache is 55 also limited to storing a single variant (see HTTP Vary: header) of each 56 resource in the cache.</div> 57 </div> 58 <div id="quickview"><h3 class="directives">Directives</h3> 59 <ul id="toc"> 60 <li><img alt="" src="../images/down.gif" /> <a href="#mcachemaxobjectcount">MCacheMaxObjectCount</a></li> 61 <li><img alt="" src="../images/down.gif" /> <a href="#mcachemaxobjectsize">MCacheMaxObjectSize</a></li> 62 <li><img alt="" src="../images/down.gif" /> <a href="#mcachemaxstreamingbuffer">MCacheMaxStreamingBuffer</a></li> 63 <li><img alt="" src="../images/down.gif" /> <a href="#mcacheminobjectsize">MCacheMinObjectSize</a></li> 64 <li><img alt="" src="../images/down.gif" /> <a href="#mcacheremovalalgorithm">MCacheRemovalAlgorithm</a></li> 65 <li><img alt="" src="../images/down.gif" /> <a href="#mcachesize">MCacheSize</a></li> 66 </ul> 67 <h3>See also</h3> 68 <ul class="seealso"> 69 <li><code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code></li> 70 <li><code class="module"><a href="../mod/mod_disk_cache.html">mod_disk_cache</a></code></li> 71 </ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> 72 73 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> 74 <div class="directive-section"><h2><a name="MCacheMaxObjectCount" id="MCacheMaxObjectCount">MCacheMaxObjectCount</a> <a name="mcachemaxobjectcount" id="mcachemaxobjectcount">Directive</a></h2> 75 <table class="directive"> 76 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The maximum number of objects allowed to be placed in the 77 cache</td></tr> 78 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMaxObjectCount <var>value</var></code></td></tr> 79 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMaxObjectCount 1009</code></td></tr> 80 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr> 81 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr> 82 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr> 83 </table> 84 <p>The <code class="directive">MCacheMaxObjectCount</code> directive sets the 85 maximum number of objects to be cached. The value is used to create the 86 open hash table. If a new object needs to be inserted in the cache and 87 the maximum number of objects has been reached, an object will be 88 removed to allow the new object to be cached. The object to be removed 89 is selected using the algorithm specified by <code class="directive"><a href="#mcacheremovalalgorithm">MCacheRemovalAlgorithm</a></code>.</p> 90 91 <div class="example"><h3>Example</h3><p><code> 92 MCacheMaxObjectCount 13001 93 </code></p></div> 94 95 </div> 96 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> 97 <div class="directive-section"><h2><a name="MCacheMaxObjectSize" id="MCacheMaxObjectSize">MCacheMaxObjectSize</a> <a name="mcachemaxobjectsize" id="mcachemaxobjectsize">Directive</a></h2> 98 <table class="directive"> 99 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The maximum size (in bytes) of a document allowed in the 100 cache</td></tr> 101 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMaxObjectSize <var>bytes</var></code></td></tr> 102 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMaxObjectSize 10000</code></td></tr> 103 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr> 104 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr> 105 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr> 106 </table> 107 <p>The <code class="directive">MCacheMaxObjectSize</code> directive sets the 108 maximum allowable size, in bytes, of a document for it to be considered 109 cacheable.</p> 110 111 <div class="example"><h3>Example</h3><p><code> 112 MCacheMaxObjectSize 6400000 113 </code></p></div> 114 115 <div class="note"><h3>Note</h3> 116 <p>The value of <code class="directive">MCacheMaxObjectSize</code> must be 117 greater than the value specified by the <code class="directive"><a href="#mcacheminobjectsize">MCacheMinObjectSize</a></code> directive.</p> 118 </div> 119 120 </div> 121 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> 122 <div class="directive-section"><h2><a name="MCacheMaxStreamingBuffer" id="MCacheMaxStreamingBuffer">MCacheMaxStreamingBuffer</a> <a name="mcachemaxstreamingbuffer" id="mcachemaxstreamingbuffer">Directive</a></h2> 123 <table class="directive"> 124 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum amount of a streamed response to buffer in memory 125 before declaring the response uncacheable</td></tr> 126 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMaxStreamingBuffer <var>size_in_bytes</var></code></td></tr> 127 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMaxStreamingBuffer the smaller of 100000 or MCacheMaxObjectSize</code></td></tr> 128 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr> 129 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr> 130 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr> 131 </table> 132 <p>The <code class="directive">MCacheMaxStreamingBuffer</code> directive 133 specifies the maximum number of bytes of a streamed response to 134 buffer before deciding that the response is too big to cache. 135 A streamed response is one in which the entire content is not 136 immediately available and in which the <code>Content-Length</code> 137 may not be known. Sources of streaming responses include proxied 138 responses and the output of CGI scripts. By default, a streamed 139 response will <em>not</em> be cached unless it has a 140 <code>Content-Length</code> header. The reason for this is to 141 avoid using a large amount of memory to buffer a partial response 142 that might end up being too large to fit in the cache. 143 The <code class="directive">MCacheMaxStreamingBuffer</code> directive allows 144 buffering of streamed responses that don't contain a 145 <code>Content-Length</code> up to the specified maximum amount of 146 space. If the maximum buffer space is reached, the buffered 147 content is discarded and the attempt to cache is abandoned.</p> 148 149 <div class="note"><h3>Note:</h3> 150 <p>Using a nonzero value for <code class="directive">MCacheMaxStreamingBuffer</code> 151 will not delay the transmission of the response to the client. 152 As soon as <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> copies a block of streamed 153 content into a buffer, it sends the block on to the next output 154 filter for delivery to the client.</p> 155 </div> 156 157 <div class="example"><p><code> 158 # Enable caching of streamed responses up to 64KB:<br /> 159 MCacheMaxStreamingBuffer 65536 160 </code></p></div> 161 162 </div> 163 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> 164 <div class="directive-section"><h2><a name="MCacheMinObjectSize" id="MCacheMinObjectSize">MCacheMinObjectSize</a> <a name="mcacheminobjectsize" id="mcacheminobjectsize">Directive</a></h2> 165 <table class="directive"> 166 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The minimum size (in bytes) of a document to be allowed in the 167 cache</td></tr> 168 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheMinObjectSize <var>bytes</var></code></td></tr> 169 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheMinObjectSize 1</code></td></tr> 170 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr> 171 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr> 172 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr> 173 </table> 174 <p>The <code class="directive">MCacheMinObjectSize</code> directive sets the 175 minimum size in bytes of a document for it to be considered 176 cacheable.</p> 177 178 <div class="example"><h3>Example</h3><p><code> 179 MCacheMinObjectSize 10000 180 </code></p></div> 181 182 </div> 183 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> 184 <div class="directive-section"><h2><a name="MCacheRemovalAlgorithm" id="MCacheRemovalAlgorithm">MCacheRemovalAlgorithm</a> <a name="mcacheremovalalgorithm" id="mcacheremovalalgorithm">Directive</a></h2> 185 <table class="directive"> 186 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The algorithm used to select documents for removal from the 187 cache</td></tr> 188 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheRemovalAlgorithm LRU|GDSF</code></td></tr> 189 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheRemovalAlgorithm GDSF</code></td></tr> 190 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr> 191 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr> 192 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr> 193 </table> 194 <p>The <code class="directive">MCacheRemovalAlgorithm</code> directive specifies 195 the algorithm used to select documents for removal from the cache. 196 Two choices are available:</p> 197 198 <dl> 199 <dt><code>LRU</code> (Least Recently Used)</dt> 200 <dd><code>LRU</code> removes the documents that have not been accessed 201 for the longest time.</dd> 202 203 <dt><code>GDSF</code> (GreadyDual-Size)</dt> 204 <dd><code>GDSF</code> assigns a priority to cached documents based 205 on the cost of a cache miss and the size of the document. Documents 206 with the lowest priority are removed first.</dd> 207 </dl> 208 209 <div class="example"><h3>Example</h3><p><code> 210 MCacheRemovalAlgorithm GDSF<br /> 211 MCacheRemovalAlgorithm LRU 212 </code></p></div> 213 214 </div> 215 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> 216 <div class="directive-section"><h2><a name="MCacheSize" id="MCacheSize">MCacheSize</a> <a name="mcachesize" id="mcachesize">Directive</a></h2> 217 <table class="directive"> 218 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The maximum amount of memory used by the cache in 219 KBytes</td></tr> 220 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>MCacheSize <var>KBytes</var></code></td></tr> 221 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>MCacheSize 100</code></td></tr> 222 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr> 223 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr> 224 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_mem_cache</td></tr> 225 </table> 226 <p>The <code class="directive">MCacheSize</code> directive sets the maximum 227 amount of memory to be used by the cache, in KBytes (1024-byte units). 228 If a new object needs to be inserted in the cache and the size of the 229 object is greater than the remaining memory, objects will be removed 230 until the new object can be cached. The object to be removed is 231 selected using the algorithm specified by <code class="directive"><a href="#mcacheremovalalgorithm">MCacheRemovalAlgorithm</a></code>.</p> 232 233 <div class="example"><h3>Example</h3><p><code> 234 MCacheSize 700000 235 </code></p></div> 236 237 <div class="note"><h3>Note</h3> 238 <p>The <code class="directive">MCacheSize</code> value must be greater than 239 the value specified by the <code class="directive"><a href="#mcachemaxobjectsize">MCacheMaxObjectSize</a></code> directive.</p> 240 </div> 241 242 </div> 243 </div> 244 <div class="bottomlang"> 245 <p><span>Available Languages: </span><a href="../en/mod/mod_mem_cache.html" title="English"> en </a> | 246 <a href="../ja/mod/mod_mem_cache.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 247 <a href="../ko/mod/mod_mem_cache.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p> 248 </div><div class="top"><a href="#page-header"><img src="../images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. Comments placed here should be pointed towards suggestions on improving the documentation or server, and may be removed again by our moderators if they are either implemented or considered invalid/off-topic. Questions on how to manage the Apache HTTP Server should be directed at either our IRC channel, #httpd, on Freenode, or sent to our <a href="http://httpd.apache.org/lists.html">mailing lists</a>.</div> 249 <script type="text/javascript"><!--//--><![CDATA[//><!-- 250 var comments_shortname = 'httpd'; 251 var comments_identifier = 'http://httpd.apache.org/docs/2.2/mod/mod_mem_cache.html'; 252 (function(w, d) { 253 if (w.location.hostname.toLowerCase() == "httpd.apache.org") { 254 d.write('<div id="comments_thread"><\/div>'); 255 var s = d.createElement('script'); 256 s.type = 'text/javascript'; 257 s.async = true; 258 s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier; 259 (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s); 260 } 261 else { 262 d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>'); 263 } 264 })(window, document); 265 //--><!]]></script></div><div id="footer"> 266 <p class="apache">Copyright 2017 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p> 267 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div><script type="text/javascript"><!--//--><![CDATA[//><!-- 268 if (typeof(prettyPrint) !== 'undefined') { 269 prettyPrint(); 270 } 271 //--><!]]></script> 272 </body></html>