docs/manual/mod/mod_buffer.html.en.utf8

<!DOCTYPE html SYSTEM "about:legacy-compat">
<html lang="en"><head><META http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta content="width=device-width, initial-scale=1" name="viewport">
<!--
        XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
              This file is generated from xml source: DO NOT EDIT
        XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
      -->
<title>mod_buffer - Apache HTTP Server Version 2.5</title>
<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet">
<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size">
<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">
<script src="../style/scripts/prettify.min.js">
</script>

<link href="../images/favicon.png" rel="shortcut icon"></head>
<body>
<div id="page-header">
<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="https://cwiki.apache.org/confluence/display/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a> | <a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2">Report a bug</a></p>
<p class="apache">Apache HTTP Server Version 2.5</p>
<img alt="" src="../images/feather.png"></div>
<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif"></a></div>
<div id="path">
<a href="https://www.apache.org/">Apache</a> &gt; <a href="https://httpd.apache.org/">HTTP Server</a> &gt; <a href="https://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.5</a> &gt; <a href="./">Modules</a></div>
<div id="page-content">
<div id="preamble"><h1>Apache Module mod_buffer</h1>
<button aria-label="Toggle language list" class="lang-toggle"><svg xmlns="http://www.w3.org/2000/svg" stroke-width="2" stroke="currentColor" fill="none" viewBox="0 0 24 24" height="16" width="16"><circle r="10" cy="12" cx="12"/><line y2="12" x2="22" y1="12" x1="2"/><path d="M12 2a15.3 15.3 0 0 1 4 10 15.3 15.3 0 0 1-4 10 15.3 15.3 0 0 1-4-10 15.3 15.3 0 0 1 4-10z"/></svg></button>
<div class="toplang">
<p><span>Available Languages: </span><a href="../en/mod/mod_buffer.html" title="English">&nbsp;en&nbsp;</a> |
<a href="../fr/mod/mod_buffer.html" hreflang="fr" rel="alternate" title="Fran&ccedil;ais">&nbsp;fr&nbsp;</a></p>
</div>
<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Support for request buffering</td></tr>
<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="module-dict.html#ModuleIdentifier">Module&nbsp;Identifier:</a></th><td>buffer_module</td></tr>
<tr><th><a href="module-dict.html#SourceFile">Source&nbsp;File:</a></th><td>mod_buffer.c</td></tr>
<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Available in Apache 2.3 and later</td></tr></table>
<h3>Summary</h3>

    <p>This module provides the ability to buffer the input and output
    filter stacks.</p>

    <p>Under certain circumstances, content generators might create
    content in small chunks. In order to promote memory reuse, in
    memory chunks are always 8k in size, regardless of the size of the
    chunk itself. When many small chunks are generated by a request,
    this can create a large memory footprint while the request is
    being processed, and an unnecessarily large amount of data on the
    wire. The addition of a buffer collapses the response into the
    fewest chunks possible.</p>

    <p>When httpd is used in front of an expensive content generator,
    buffering the response may allow the backend to complete
    processing and release resources sooner, depending on how the
    backend is designed.</p>

    <p>The buffer filter may be added to either the input or the
    output filter stacks, as appropriate, using the
    <code class="directive"><a href="../mod/core.html#setinputfilter">SetInputFilter</a></code>,
    <code class="directive"><a href="../mod/core.html#setoutputfilter">SetOutputFilter</a></code>,
    <code class="directive"><a href="../mod/mod_mime.html#addoutputfilter">AddOutputFilter</a></code> or
    <code class="directive"><a href="../mod/mod_filter.html#addoutputfilterbytype">AddOutputFilterByType</a></code> directives.</p>

      <div class="example"><h3>Using buffer with mod_include</h3><pre class="prettyprint lang-config">AddOutputFilterByType INCLUDES;BUFFER text/html</pre>
</div>

    <div class="warning">The buffer filters read the request/response into
        RAM and then repack the request/response into the fewest memory
        buckets possible, at the cost of CPU time. When the request/response
        is already efficiently packed, buffering the request/response could
        cause the request/response to be slower than not using a buffer at
        all. These filters should be used with care, and only where
        necessary.</div>

</div>
<div id="quickview"><h3 class="directives">Directives</h3>
<ul id="toc">
<li><img alt="" src="../images/down.gif"> <a href="#buffersize">BufferSize</a></li>
</ul>
<h3>Bugfix checklist</h3><ul class="seealso"><li><a href="https://www.apache.org/dist/httpd/CHANGES_2.4">httpd changelog</a></li><li><a href="https://bz.apache.org/bugzilla/buglist.cgi?bug_status=__open__&amp;list_id=144532&amp;product=Apache%20httpd-2&amp;query_format=specific&amp;order=changeddate%20DESC%2Cpriority%2Cbug_severity&amp;component=mod_buffer">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&amp;component=mod_buffer">Report a bug</a></li></ul><h3>See also</h3>
<ul class="seealso">
<li><a href="../filter.html">Filters</a></li>
</ul></div>

<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif"></a></div>
<div class="directive-section"><h2 id="buffersize"><span id="BufferSize">BufferSize</span> Directive <a title="Permanent link" href="#buffersize" class="permalink">&para;</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Maximum size in bytes to buffer by the buffer filter</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>BufferSize integer</code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>BufferSize 131072</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>directory, .htaccess</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Extension</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_buffer</td></tr>
</table>
    <p>The <code class="directive">BufferSize</code>
    directive specifies the amount of data in bytes that will be
    buffered before being read from or written to each request.
    The default is 128 kilobytes.</p>

</div>
</div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="../en/mod/mod_buffer.html" title="English">&nbsp;en&nbsp;</a> |
<a href="../fr/mod/mod_buffer.html" hreflang="fr" rel="alternate" title="Fran&ccedil;ais">&nbsp;fr&nbsp;</a></p>
</div><div id="footer">
<p class="apache">Copyright 2026 The Apache Software Foundation.<br>Licensed under the <a href="https://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/quickreference.html">Directives</a> | <a href="https://cwiki.apache.org/confluence/display/httpd/FAQ">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a> | <a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2">Report a bug</a></p></div><script><!--//--><![CDATA[//><!--
if (typeof(prettyPrint) !== 'undefined') {
    prettyPrint();
}
var langToggle = document.querySelector('.lang-toggle');
var topLang = document.querySelector('.toplang');
if (langToggle && topLang) {
    langToggle.addEventListener('click', function() { topLang.classList.toggle('open'); });
}
var qv = document.getElementById('quickview');
if (qv) {
    document.body.appendChild(qv);
    var qvBtn = document.createElement('button');
    qvBtn.className = 'qv-toggle';
    qvBtn.setAttribute('aria-label', 'Toggle page navigation');
    qvBtn.innerHTML = '&#9776;';
    document.body.appendChild(qvBtn);
    qvBtn.addEventListener('click', function() {
        var isOpen = qv.classList.toggle('open');
        if (isOpen) {
            qv.style.top = window.scrollY + 10 + 'px';
        }
    });
    window.addEventListener('scroll', function() { qv.classList.remove('open'); });
}
//--><!]]></script>
</body></html>