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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 06:33:50 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 06:33:50 +0000 |
| commit | fe39ffb8b90ae4e002ed73fe98617cd590abb467 (patch) | |
| tree | b80e5956907d8aeaaffe4e4f0c068c0e6157ce8b /docs/manual/mod/mod_lbmethod_byrequests.html.en | |
| parent | Initial commit. (diff) | |
| download | apache2-fe39ffb8b90ae4e002ed73fe98617cd590abb467.tar.xz apache2-fe39ffb8b90ae4e002ed73fe98617cd590abb467.zip | |
Adding upstream version 2.4.56.upstream/2.4.56
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'docs/manual/mod/mod_lbmethod_byrequests.html.en')
| -rw-r--r-- | docs/manual/mod/mod_lbmethod_byrequests.html.en | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/docs/manual/mod/mod_lbmethod_byrequests.html.en b/docs/manual/mod/mod_lbmethod_byrequests.html.en new file mode 100644 index 0000000..52fd1f1 --- /dev/null +++ b/docs/manual/mod/mod_lbmethod_byrequests.html.en @@ -0,0 +1,255 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head> +<meta content="text/html; charset=UTF-8" http-equiv="Content-Type" /> +<!-- + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + This file is generated from xml source: DO NOT EDIT + XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX + --> +<title>mod_lbmethod_byrequests - Apache HTTP Server Version 2.4</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" type="text/javascript"> +</script> + +<link href="../images/favicon.ico" rel="shortcut icon" /></head> +<body> +<div id="page-header"> +<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> +<p class="apache">Apache HTTP Server Version 2.4</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="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 2.4</a> > <a href="./">Modules</a></div> +<div id="page-content"> +<div id="preamble"><h1>Apache Module mod_lbmethod_byrequests</h1> +<div class="toplang"> +<p><span>Available Languages: </span><a href="../en/mod/mod_lbmethod_byrequests.html" title="English"> en </a> | +<a href="../fr/mod/mod_lbmethod_byrequests.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p> +</div> +<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Request Counting load balancer scheduler algorithm for <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code></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 Identifier:</a></th><td>lbmethod_byrequests_module</td></tr> +<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_lbmethod_byrequests.c</td></tr> +<tr><th><a href="module-dict.html#Compatibility">Compatibility:</a></th><td>Split off from <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> in 2.3</td></tr></table> +<h3>Summary</h3> + +<p>This module does not provide any configuration directives of its own. +It requires the services of <code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code>, and +provides the <code>byrequests</code> load balancing method.</p> +</div> +<div id="quickview"><a href="https://www.apache.org/foundation/contributing.html" class="badge"><img src="https://www.apache.org/images/SupportApache-small.png" alt="Support Apache!" /></a><h3>Topics</h3> +<ul id="topics"> +<li><img alt="" src="../images/down.gif" /> <a href="#requests">Request Counting Algorithm</a></li> +</ul><h3 class="directives">Directives</h3> +<p>This module provides no + directives.</p> +<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__&list_id=144532&product=Apache%20httpd-2&query_format=specific&order=changeddate%20DESC%2Cpriority%2Cbug_severity&component=mod_lbmethod_byrequests">Known issues</a></li><li><a href="https://bz.apache.org/bugzilla/enter_bug.cgi?product=Apache%20httpd-2&component=mod_lbmethod_byrequests">Report a bug</a></li></ul><h3>See also</h3> +<ul class="seealso"> +<li><code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code></li> +<li><code class="module"><a href="../mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code></li> +<li><a href="#comments_section">Comments</a></li></ul></div> +<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div> +<div class="section"> +<h2><a name="requests" id="requests">Request Counting Algorithm</a></h2> + + <p>Enabled via <code>lbmethod=byrequests</code>, the idea behind this + scheduler is that we distribute the requests among the + various workers to ensure that each gets their configured share + of the number of requests. It works as follows:</p> + + <p><dfn>lbfactor</dfn> is <em>how much we expect this worker + to work</em>, or <em>the workers' work quota</em>. This is + a normalized value representing their "share" of the amount of + work to be done.</p> + + <p><dfn>lbstatus</dfn> is <em>how urgent this worker has to work + to fulfill its quota of work</em>.</p> + + <p>The <dfn>worker</dfn> is a member of the load balancer, + usually a remote host serving one of the supported protocols.</p> + + <p>We distribute each worker's work quota to the worker, and then look + which of them needs to work most urgently (biggest lbstatus). This + worker is then selected for work, and its lbstatus reduced by the + total work quota we distributed to all workers. Thus the sum of all + lbstatus does not change(*) and we distribute the requests + as desired.</p> + + <p>If some workers are disabled, the others will + still be scheduled correctly.</p> + + <div class="example"><pre><code>for each worker in workers + worker lbstatus += worker lbfactor + total factor += worker lbfactor + if worker lbstatus > candidate lbstatus + candidate = worker + +candidate lbstatus -= total factor</code></pre></div> + + <p>If a balancer is configured as follows:</p> + + <table><tr><th>worker</th> + <th class="data">a</th> + <th class="data">b</th> + <th class="data">c</th> + <th class="data">d</th></tr> +<tr><th>lbfactor</th> + <td class="data">25</td> + <td class="data">25</td> + <td class="data">25</td> + <td class="data">25</td></tr> +<tr><th>lbstatus</th> + <td class="data">0</td> + <td class="data">0</td> + <td class="data">0</td> + <td class="data">0</td></tr> +</table> + + <p>And <var>b</var> gets disabled, the following schedule is produced:</p> + + <table><tr><th>worker</th> + <th class="data">a</th> + <th class="data">b</th> + <th class="data">c</th> + <th class="data">d</th></tr> +<tr><th>lbstatus</th> + <td class="data"><em>-50</em></td> + <td class="data">0</td> + <td class="data">25</td> + <td class="data">25</td></tr> +<tr><th>lbstatus</th> + <td class="data">-25</td> + <td class="data">0</td> + <td class="data"><em>-25</em></td> + <td class="data">50</td></tr> +<tr><th>lbstatus</th> + <td class="data">0</td> + <td class="data">0</td> + <td class="data">0</td> + <td class="data"><em>0</em></td></tr> +<tr><td class="data" colspan="5">(repeat)</td></tr> +</table> + + <p>That is it schedules: <var>a</var> <var>c</var> <var>d</var> + <var>a</var> <var>c</var> <var>d</var> <var>a</var> <var>c</var> + <var>d</var> ... Please note that:</p> + + <table><tr><th>worker</th> + <th class="data">a</th> + <th class="data">b</th> + <th class="data">c</th> + <th class="data">d</th></tr> +<tr><th>lbfactor</th> + <td class="data">25</td> + <td class="data">25</td> + <td class="data">25</td> + <td class="data">25</td></tr> +</table> + + <p>Has the exact same behavior as:</p> + + <table><tr><th>worker</th> + <th class="data">a</th> + <th class="data">b</th> + <th class="data">c</th> + <th class="data">d</th></tr> +<tr><th>lbfactor</th> + <td class="data">1</td> + <td class="data">1</td> + <td class="data">1</td> + <td class="data">1</td></tr> +</table> + + <p>This is because all values of <dfn>lbfactor</dfn> are normalized + with respect to the others. For:</p> + + <table><tr><th>worker</th> + <th class="data">a</th> + <th class="data">b</th> + <th class="data">c</th></tr> +<tr><th>lbfactor</th> + <td class="data">1</td> + <td class="data">4</td> + <td class="data">1</td></tr> +</table> + + <p>worker <var>b</var> will, on average, get 4 times the requests + that <var>a</var> and <var>c</var> will.</p> + + <p>The following asymmetric configuration works as one would expect:</p> + + <table><tr><th>worker</th> + <th class="data">a</th> + <th class="data">b</th></tr> +<tr><th>lbfactor</th> + <td class="data">70</td> + <td class="data">30</td></tr> +<tr><td class="data" colspan="2"> </td></tr> +<tr><th>lbstatus</th> + <td class="data"><em>-30</em></td> + <td class="data">30</td></tr> +<tr><th>lbstatus</th> + <td class="data">40</td> + <td class="data"><em>-40</em></td></tr> +<tr><th>lbstatus</th> + <td class="data"><em>10</em></td> + <td class="data">-10</td></tr> +<tr><th>lbstatus</th> + <td class="data"><em>-20</em></td> + <td class="data">20</td></tr> +<tr><th>lbstatus</th> + <td class="data"><em>-50</em></td> + <td class="data">50</td></tr> +<tr><th>lbstatus</th> + <td class="data">20</td> + <td class="data"><em>-20</em></td></tr> +<tr><th>lbstatus</th> + <td class="data"><em>-10</em></td> + <td class="data">10</td></tr> +<tr><th>lbstatus</th> + <td class="data"><em>-40</em></td> + <td class="data">40</td></tr> +<tr><th>lbstatus</th> + <td class="data">30</td> + <td class="data"><em>-30</em></td></tr> +<tr><th>lbstatus</th> + <td class="data"><em>0</em></td> + <td class="data">0</td></tr> +<tr><td class="data" colspan="3">(repeat)</td></tr> +</table> + + <p>That is after 10 schedules, the schedule repeats and 7 <var>a</var> + are selected with 3 <var>b</var> interspersed.</p> +</div> +</div> +<div class="bottomlang"> +<p><span>Available Languages: </span><a href="../en/mod/mod_lbmethod_byrequests.html" title="English"> en </a> | +<a href="../fr/mod/mod_lbmethod_byrequests.html" hreflang="fr" rel="alternate" title="Français"> fr </a></p> +</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 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 Libera.chat, or sent to our <a href="https://httpd.apache.org/lists.html">mailing lists</a>.</div> +<script type="text/javascript"><!--//--><![CDATA[//><!-- +var comments_shortname = 'httpd'; +var comments_identifier = 'http://httpd.apache.org/docs/2.4/mod/mod_lbmethod_byrequests.html'; +(function(w, d) { + if (w.location.hostname.toLowerCase() == "httpd.apache.org") { + d.write('<div id="comments_thread"><\/div>'); + var s = d.createElement('script'); + s.type = 'text/javascript'; + s.async = true; + s.src = 'https://comments.apache.org/show_comments.lua?site=' + comments_shortname + '&page=' + comments_identifier; + (d.getElementsByTagName('head')[0] || d.getElementsByTagName('body')[0]).appendChild(s); + } + else { + d.write('<div id="comments_thread">Comments are disabled for this page at the moment.<\/div>'); + } +})(window, document); +//--><!]]></script></div><div id="footer"> +<p class="apache">Copyright 2023 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> +<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[//><!-- +if (typeof(prettyPrint) !== 'undefined') { + prettyPrint(); +} +//--><!]]></script> +</body></html>
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