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| 771 | blopes | 1 | <!DOCTYPE html SYSTEM "about:legacy-compat"> |
| 2 | <html lang="en"><head><META http-equiv="Content-Type" content="text/html; charset=UTF-8"><link href="../images/docs-stylesheet.css" rel="stylesheet" type="text/css"><title>Apache Tomcat 9 Configuration Reference (9.0.112) - The Executor (thread pool)</title></head><body><div id="wrapper"><header><div id="header"><div><div><div class="logo noPrint"><a href="https://tomcat.apache.org/"><img alt="Tomcat Home" src="../images/tomcat.png"></a></div><div style="height: 1px;"></div><div class="asfLogo noPrint"><a href="https://www.apache.org/" target="_blank"><img src="../images/asf-logo.svg" alt="The Apache Software Foundation" style="width: 266px; height: 83px;"></a></div><h1>Apache Tomcat 9 Configuration Reference</h1><div class="versionInfo"> |
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| 3 | Version 9.0.112, |
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| 4 | <time datetime="2025-11-06">Nov 6 2025</time></div><div style="height: 1px;"></div><div style="clear: left;"></div></div></div></div></header><div id="middle"><div><div id="mainLeft" class="noprint"><div><nav><div><h2>Links</h2><ul><li><a href="../index.html">Docs Home</a></li><li><a href="index.html">Config Ref. Home</a></li><li><a href="https://cwiki.apache.org/confluence/display/TOMCAT/FAQ">FAQ</a></li><li><a href="#comments_section">User Comments</a></li></ul></div><div><h2>Top Level Elements</h2><ul><li><a href="server.html">Server</a></li><li><a href="service.html">Service</a></li></ul></div><div><h2>Executors</h2><ul><li><a href="executor.html">Executor</a></li></ul></div><div><h2>Connectors</h2><ul><li><a href="http.html">HTTP/1.1</a></li><li><a href="http2.html">HTTP/2</a></li><li><a href="ajp.html">AJP</a></li></ul></div><div><h2>Containers</h2><ul><li><a href="context.html">Context</a></li><li><a href="engine.html">Engine</a></li><li><a href="host.html">Host</a></li><li><a href="cluster.html">Cluster</a></li></ul></div><div><h2>Nested Components</h2><ul><li><a href="cookie-processor.html">CookieProcessor</a></li><li><a href="credentialhandler.html">CredentialHandler</a></li><li><a href="globalresources.html">Global Resources</a></li><li><a href="jar-scanner.html">JarScanner</a></li><li><a href="jar-scan-filter.html">JarScanFilter</a></li><li><a href="listeners.html">Listeners</a></li><li><a href="loader.html">Loader</a></li><li><a href="manager.html">Manager</a></li><li><a href="realm.html">Realm</a></li><li><a href="resources.html">Resources</a></li><li><a href="sessionidgenerator.html">SessionIdGenerator</a></li><li><a href="valve.html">Valve</a></li></ul></div><div><h2>Cluster Elements</h2><ul><li><a href="cluster.html">Cluster</a></li><li><a href="cluster-manager.html">Manager</a></li><li><a href="cluster-channel.html">Channel</a></li><li><a href="cluster-membership.html">Channel/Membership</a></li><li><a href="cluster-sender.html">Channel/Sender</a></li><li><a href="cluster-receiver.html">Channel/Receiver</a></li><li><a href="cluster-interceptor.html">Channel/Interceptor</a></li><li><a href="cluster-valve.html">Valve</a></li><li><a href="cluster-deployer.html">Deployer</a></li><li><a href="cluster-listener.html">ClusterListener</a></li></ul></div><div><h2>web.xml</h2><ul><li><a href="filter.html">Filter</a></li></ul></div><div><h2>Other</h2><ul><li><a href="runtime-attributes.html">Runtime attributes</a></li><li><a href="systemprops.html">System properties</a></li><li><a href="jaspic.html">JASPIC</a></li></ul></div></nav></div></div><div id="mainRight"><div id="content"><h2>The Executor (thread pool)</h2><h3 id="Table_of_Contents">Table of Contents</h3><div class="text"> |
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| 5 | <ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Attributes">Attributes</a><ol><li><a href="#Common_Attributes">Common Attributes</a></li><li><a href="#Standard_Implementation">Standard Implementation</a></li><li><a href="#Virtual_Thread_Implementation">Virtual Thread Implementation</a></li></ol></li></ul> |
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| 6 | </div><h3 id="Introduction">Introduction</h3><div class="text"> |
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| 7 | |||
| 8 | <p>The <strong>Executor</strong> represents a thread pool that can be shared |
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| 9 | between components in Tomcat. Historically there has been a thread pool per |
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| 10 | connector created but this allows you to share a thread pool, between (primarily) connector |
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| 11 | but also other components when those get configured to support executors</p> |
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| 12 | |||
| 13 | |||
| 14 | <p>The executor has to implement the <code>org.apache.catalina.Executor</code> interface.</p> |
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| 15 | |||
| 16 | <p>The executor is a nested element to the <a href="service.html">Service</a> element. |
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| 17 | And in order for it to be picked up by the connectors, the Executor element has to appear |
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| 18 | prior to the Connector element in server.xml</p> |
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| 19 | </div><h3 id="Attributes">Attributes</h3><div class="text"> |
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| 20 | |||
| 21 | <div class="subsection"><h4 id="Common_Attributes">Common Attributes</h4><div class="text"> |
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| 22 | |||
| 23 | <p>All implementations of <strong>Executor</strong> |
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| 24 | support the following attributes:</p> |
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| 25 | |||
| 26 | <table class="defaultTable"><tr><th style="width: 15%;"> |
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| 27 | Attribute |
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| 28 | </th><th style="width: 85%;"> |
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| 29 | Description |
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| 30 | </th></tr><tr id="Attributes_Common Attributes_className"><td><code class="attributeName">className</code></td><td> |
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| 31 | <p>The class of the implementation. The implementation has to implement the |
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| 32 | <code>org.apache.catalina.Executor</code> interface. |
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| 33 | This interface ensures that the object can be referenced through its <code>name</code> attribute |
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| 34 | and that implements Lifecycle, so that it can be started and stopped with the container. |
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| 35 | The default value for the className is <code>org.apache.catalina.core.StandardThreadExecutor</code></p> |
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| 36 | </td></tr><tr id="Attributes_Common Attributes_name"><td><strong><code class="attributeName">name</code></strong></td><td> |
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| 37 | <p>The name used to reference this pool in other places in server.xml. |
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| 38 | The name is required and must be unique.</p> |
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| 39 | </td></tr></table> |
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| 40 | |||
| 41 | </div></div> |
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| 42 | |||
| 43 | <div class="subsection"><h4 id="Standard_Implementation">Standard Implementation</h4><div class="text"> |
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| 44 | |||
| 45 | <p>This implementation uses a pool of platform threads to execute the tasks assigned to the Executor.</p> |
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| 46 | |||
| 47 | <p>The <code>className</code> attribute must be <code>org.apache.catalina.core.StandardThreadExecutor</code> to use |
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| 48 | this implementation.</p> |
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| 49 | |||
| 50 | <p>The standard implementation supports the following attributes:</p> |
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| 51 | |||
| 52 | <table class="defaultTable"><tr><th style="width: 15%;"> |
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| 53 | Attribute |
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| 54 | </th><th style="width: 85%;"> |
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| 55 | Description |
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| 56 | </th></tr><tr id="Attributes_Standard Implementation_threadPriority"><td><code class="attributeName">threadPriority</code></td><td> |
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| 57 | <p>(int) The thread priority for threads in the executor, the default is |
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| 58 | <code>5</code> (the value of the <code>Thread.NORM_PRIORITY</code> constant)</p> |
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| 59 | </td></tr><tr id="Attributes_Standard Implementation_daemon"><td><code class="attributeName">daemon</code></td><td> |
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| 60 | <p>(boolean) Whether the threads should be daemon threads or not, the default is <code>true</code></p> |
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| 61 | </td></tr><tr id="Attributes_Standard Implementation_namePrefix"><td><code class="attributeName">namePrefix</code></td><td> |
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| 62 | <p>(String) The name prefix for each thread created by the executor. |
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| 63 | The thread name for an individual thread will be <code>namePrefix+threadNumber</code>. The default value is |
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| 64 | <code>tomcat-exec-</code>.</p> |
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| 65 | </td></tr><tr id="Attributes_Standard Implementation_maxThreads"><td><code class="attributeName">maxThreads</code></td><td> |
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| 66 | <p>(int) The max number of active threads in this pool, default is <code>200</code></p> |
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| 67 | </td></tr><tr id="Attributes_Standard Implementation_minSpareThreads"><td><code class="attributeName">minSpareThreads</code></td><td> |
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| 68 | <p>(int) The minimum number of threads (idle and active) always kept alive, default is <code>25</code></p> |
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| 69 | </td></tr><tr id="Attributes_Standard Implementation_maxIdleTime"><td><code class="attributeName">maxIdleTime</code></td><td> |
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| 70 | <p>(int) The number of milliseconds before an idle thread shutsdown, unless the number of active threads are less |
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| 71 | or equal to minSpareThreads. Default value is <code>60000</code>(1 minute)</p> |
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| 72 | </td></tr><tr id="Attributes_Standard Implementation_maxQueueSize"><td><code class="attributeName">maxQueueSize</code></td><td> |
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| 73 | <p>(int) The maximum number of runnable tasks that can queue up awaiting |
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| 74 | execution before we reject them. Default value is <code>Integer.MAX_VALUE</code></p> |
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| 75 | </td></tr><tr id="Attributes_Standard Implementation_threadRenewalDelay"><td><code class="attributeName">threadRenewalDelay</code></td><td> |
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| 76 | <p>(long) If a <a href="listeners.html">ThreadLocalLeakPreventionListener</a> is configured, |
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| 77 | it will notify this executor about stopped contexts. |
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| 78 | After a context is stopped, threads in the pool are renewed. To avoid renewing all threads at the same time, |
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| 79 | this option sets a delay between renewal of any 2 threads. The value is in ms, |
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| 80 | default value is <code>1000</code> ms. If value is negative, threads are not renewed.</p> |
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| 81 | </td></tr></table> |
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| 82 | |||
| 83 | |||
| 84 | </div></div> |
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| 85 | |||
| 86 | <div class="subsection"><h4 id="Virtual_Thread_Implementation">Virtual Thread Implementation</h4><div class="text"> |
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| 87 | |||
| 88 | <p>This implementation uses a new virtual thread to execute each task assigned to the Executor. This Executor requires |
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| 89 | a minimum Java version of Java 21.</p> |
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| 90 | |||
| 91 | <p>The <code>className</code> attribute must be <code>org.apache.catalina.core.StandardVirtualThreadExecutor</code> to |
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| 92 | use this implementation.</p> |
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| 93 | |||
| 94 | <p>The virtual thread implementation supports the follow attributes:</p> |
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| 95 | |||
| 96 | <table class="defaultTable"><tr><th style="width: 15%;"> |
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| 97 | Attribute |
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| 98 | </th><th style="width: 85%;"> |
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| 99 | Description |
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| 100 | </th></tr><tr id="Attributes_Virtual Thread Implementation_namePrefix"><td><code class="attributeName">namePrefix</code></td><td> |
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| 101 | <p>(String) The name prefix for each thread created by the executor. |
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| 102 | The thread name for an individual thread will be <code>namePrefix+threadNumber</code>. The default value is |
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| 103 | <code>tomcat-virt-</code></p> |
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| 104 | </td></tr></table> |
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| 105 | |||
| 106 | </div></div> |
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| 107 | |||
| 108 | </div></div></div></div></div><footer><div id="footer"> |
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| 109 | Copyright © 1999-2025, The Apache Software Foundation |
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| 110 | <br> |
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| 111 | Apache Tomcat, Tomcat, Apache, the Apache Tomcat logo and the Apache logo |
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| 112 | are either registered trademarks or trademarks of the Apache Software |
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| 113 | Foundation. |
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| 114 | </div></footer></div></body></html> |