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| <title>The L1 Session Cache</title><link rel="stylesheet" type="text/css" href="css/docbook.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><meta name="keywords" content="jetty, servlet, servlet-api, cometd, http, websocket, eclipse, maven, java, server, software"><link rel="home" href="index.html" title="Jetty"><link rel="up" href="session-management.html" title="Chapter 10. Session Management"><link rel="prev" href="session-configuration-housekeeper.html" title="The SessionIdManager and the Housekeeper"><link rel="next" href="configuring-sessions-memory.html" title="Non-Persistent Sessions"><link xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" rel="shortcut icon" href="images/favicon.ico"><link rel="stylesheet" href="css/highlighter/foundation.css"><script src="js/highlight.pack.js"></script><script> |
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| Version: 9.4.28-SNAPSHOT</span></td><td style="width: 50%"></td></tr></table><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">The L1 Session Cache</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="session-configuration-housekeeper.html"><i class="fa fa-chevron-left" aria-hidden="true"></i> Previous</a> </td><th width="60%" align="center">Chapter 10. Session Management<br><a accesskey="p" href="index.html"><i class="fa fa-home" aria-hidden="true"></i> Home</a></th><td width="20%" align="right"> <a accesskey="n" href="configuring-sessions-memory.html">Next <i class="fa fa-chevron-right" aria-hidden="true"></i></a></td></tr></table><hr></div><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="jetty-callout"><h5 class="callout"><a href="http://www.webtide.com/">Contact the core Jetty developers at |
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| </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="session-configuration-sessioncache"></a>The L1 Session Cache</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="session-configuration-sessioncache.html#_the_defaultsessioncache">The DefaultSessionCache</a></span></dt><dt><span class="section"><a href="session-configuration-sessioncache.html#_the_nullsessioncache">The NullSessionCache</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_the_defaultsessioncache"></a>The DefaultSessionCache</h3></div></div></div><p>In the absence of any explicit configuration, Jetty will instantiate an instance of the <code class="literal">DefaultSessionCache</code> per context. |
| If you wish to change any of the default values, you need to enable the <code class="literal">session-cache-hash</code> <a class="link" href="startup-modules.html" title="Managing Startup Modules">module</a>.</p><p>Once the <code class="literal">session-cache-hash</code> module has been enabled, you can view a list of all the configurable values by opening <code class="literal">start.d/session-cache-hash.ini</code>:</p><div class="screenexample"><pre class="screen">--module=session-cache-hash |
| |
| #jetty.session.evictionPolicy=-1 |
| #jetty.session.saveOnInactiveEvict=false |
| #jetty.session.saveOnCreate=false |
| #jetty.session.removeUnloadableSessions=false |
| #jetty.session.flushOnResponseCommit=false</pre></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">jetty.session.evictionPolicy</span></dt><dd><p class="simpara">Integer. |
| Controls whether session objects that are held in memory are subject to eviction from the memory cache. |
| Evicting sessions can reduce the memory footprint of the cache. |
| Eviction is usually used in conjunction with a <code class="literal">SessionDataStore</code> that persists sessions. |
| Values are:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">-1 : sessions are never evicted from the cache</li><li class="listitem">0 : sessions are evicted from the cache as soon as the last active request for it finishes</li><li class="listitem">>= 1 : any positive number is the time in seconds after which a session that is in the cache but has not experienced any activity will be evicted</li></ul></div></dd></dl></div><div class="blockquote"><blockquote class="blockquote"><div xmlns:jfetch="java:org.eclipse.jetty.xslt.tools.JavaSourceFetchExtension" xmlns:fetch="java:org.eclipse.jetty.xslt.tools.SourceFetchExtension" xmlns:d="http://docbook.org/ns/docbook" xmlns:l="http://docbook.sourceforge.net/xmlns/l10n/1.0" xmlns:xslthl="http://xslthl.sf.net" xmlns:gcse="http://www.google.com" xmlns:date="http://exslt.org/dates-and-times" class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><i class="fa fa-asterisk" aria-hidden="true"></i> Note</h3><p>If you are not using a <code class="literal">SessionDataStore</code> that persists sessions, be aware that evicted sessions will be lost.</p></div></blockquote></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">jetty.session.saveOnInactiveEvict</span></dt><dd>Boolean, default <code class="literal">false</code>. |
| Controls whether a session will be saved to the <code class="literal">SessionDataStore</code> just prior to its eviction.</dd><dt><span class="term">jetty.session.saveOnCreate</span></dt><dd>Boolean, default <code class="literal">false</code>. |
| Controls whether a session that is newly created will be immediately saved to the <code class="literal">SessionDataStore</code> or lazily saved as the last request for the session exits.</dd><dt><span class="term">jetty.session.removeUnloadableSessions</span></dt><dd>Boolean, default <code class="literal">false</code>. |
| Controls whether a session that cannot be restored - for example because it is corrupted - from the <code class="literal">SessionDataStore</code> is deleted by the <code class="literal">SessionDataStore</code>.</dd><dt><span class="term">jetty.session.flushOnResponseCommit</span></dt><dd>Boolean, default <code class="literal">false</code>. |
| If true, if a session is "dirty" - ie its attributes have changed - it will be written to the backing store as the response is about to commit. |
| This ensures that all subsequent requests whether to the same or different node will see the updated session data. |
| If false, a dirty session will only be written to the backing store when the last simultaneous request for it leaves the session.</dd></dl></div><p>For more general information on the uses of these configuration properties, see <a class="link" href="sessions-details.html" title="Session Components">Session Components</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="_the_nullsessioncache"></a>The NullSessionCache</h3></div></div></div><p>The <code class="literal">NullSessionCache</code> is a trivial implementation of the <code class="literal">SessionCache</code> that does not cache any session information. |
| You may need to use it if your clustering setup does not have a sticky load balancer, or if you want absolutely minimal support for sessions. |
| If you use this in conjunction with the <code class="literal">NullSessionDataStore</code>, then sessions will neither be retained in memory nor persisted.</p><p>To enable the <code class="literal">NullSessionCache</code>, enable the <code class="literal">sesssion-cache-null</code> <a class="link" href="startup-modules.html" title="Managing Startup Modules">module</a>. |
| Configuration options are:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">jetty.session.saveOnCreate</span></dt><dd>Boolean, default <code class="literal">false</code>. |
| Controls whether a session that is newly created will be immediately saved to the <code class="literal">SessionDataStore</code> or lazily saved as the last request for the session exits.</dd><dt><span class="term">jetty.session.removeUnloadableSessions</span></dt><dd>Boolean, default <code class="literal">false</code>. |
| Controls whether a session that cannot be restored - for example because it is corrupted - from the <code class="literal">SessionDataStore</code> is deleted by the <code class="literal">SessionDataStore</code>.</dd><dt><span class="term">jetty.session.flushOnResponseCommit</span></dt><dd>Boolean, default <code class="literal">false</code>. |
| If true, if a session is "dirty" - ie its attributes have changed - it will be written to the backing store as the response is about to commit. |
| This ensures that all subsequent requests whether to the same or different node will see the updated session data. |
| If false, a dirty session will only be written to the backing store when the last simultaneous request for it leaves the session.</dd></dl></div><p>For more general information on the uses of these configuration properties, see <a class="link" href="sessions-details.html" title="Session Components">Session Components</a>.</p></div></div><script type="text/javascript"> |
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