Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 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 (9.0.112) - Advanced IO and Tomcat</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</h1><div class="versionInfo"> |
||
| 3 | Version 9.0.112, |
||
| 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="https://cwiki.apache.org/confluence/display/TOMCAT/FAQ">FAQ</a></li></ul></div><div><h2>User Guide</h2><ul><li><a href="introduction.html">1) Introduction</a></li><li><a href="setup.html">2) Setup</a></li><li><a href="appdev/index.html">3) First webapp</a></li><li><a href="deployer-howto.html">4) Deployer</a></li><li><a href="manager-howto.html">5) Manager</a></li><li><a href="host-manager-howto.html">6) Host Manager</a></li><li><a href="realm-howto.html">7) Realms and AAA</a></li><li><a href="security-manager-howto.html">8) Security Manager</a></li><li><a href="jndi-resources-howto.html">9) JNDI Resources</a></li><li><a href="jndi-datasource-examples-howto.html">10) JDBC DataSources</a></li><li><a href="class-loader-howto.html">11) Classloading</a></li><li><a href="jasper-howto.html">12) JSPs</a></li><li><a href="ssl-howto.html">13) SSL/TLS</a></li><li><a href="ssi-howto.html">14) SSI</a></li><li><a href="cgi-howto.html">15) CGI</a></li><li><a href="proxy-howto.html">16) Proxy Support</a></li><li><a href="mbeans-descriptors-howto.html">17) MBeans Descriptors</a></li><li><a href="default-servlet.html">18) Default Servlet</a></li><li><a href="cluster-howto.html">19) Clustering</a></li><li><a href="balancer-howto.html">20) Load Balancer</a></li><li><a href="connectors.html">21) Connectors</a></li><li><a href="monitoring.html">22) Monitoring and Management</a></li><li><a href="logging.html">23) Logging</a></li><li><a href="apr.html">24) APR/Native</a></li><li><a href="virtual-hosting-howto.html">25) Virtual Hosting</a></li><li><a href="aio.html">26) Advanced IO</a></li><li><a href="maven-jars.html">27) Mavenized</a></li><li><a href="security-howto.html">28) Security Considerations</a></li><li><a href="windows-service-howto.html">29) Windows Service</a></li><li><a href="windows-auth-howto.html">30) Windows Authentication</a></li><li><a href="jdbc-pool.html">31) Tomcat's JDBC Pool</a></li><li><a href="web-socket-howto.html">32) WebSocket</a></li><li><a href="rewrite.html">33) Rewrite</a></li><li><a href="cdi.html">34) CDI 2 and JAX-RS</a></li><li><a href="graal.html">35) AOT/GraalVM Support</a></li></ul></div><div><h2>Reference</h2><ul><li><a href="RELEASE-NOTES.txt">Release Notes</a></li><li><a href="config/index.html">Configuration</a></li><li><a href="api/index.html">Tomcat Javadocs</a></li><li><a href="servletapi/index.html">Servlet 4.0 Javadocs</a></li><li><a href="jspapi/index.html">JSP 2.3 Javadocs</a></li><li><a href="elapi/index.html">EL 3.0 Javadocs</a></li><li><a href="websocketapi/index.html">WebSocket 1.1 Javadocs</a></li><li><a href="jaspicapi/index.html">JASPIC 1.1 Javadocs</a></li><li><a href="annotationapi/index.html">Common Annotations 1.3 Javadocs</a></li><li><a href="https://tomcat.apache.org/connectors-doc/">JK 1.2 Documentation</a></li></ul></div><div><h2>Apache Tomcat Development</h2><ul><li><a href="building.html">Building</a></li><li><a href="changelog.html">Changelog</a></li><li><a href="https://cwiki.apache.org/confluence/display/TOMCAT/Tomcat+Versions">Status</a></li><li><a href="developers.html">Developers</a></li><li><a href="architecture/index.html">Architecture</a></li><li><a href="tribes/introduction.html">Tribes</a></li></ul></div></nav></div></div><div id="mainRight"><div id="content"><h2>Advanced IO and Tomcat</h2><h3 id="Table_of_Contents">Table of Contents</h3><div class="text"> |
||
| 5 | <ul><li><a href="#Introduction">Introduction</a></li><li><a href="#Asynchronous_writes">Asynchronous writes</a></li></ul> |
||
| 6 | </div><h3 id="Introduction">Introduction</h3><div class="text"> |
||
| 7 | |||
| 8 | <p> |
||
| 9 | <b>IMPORTANT NOTE: Usage of these features requires using the |
||
| 10 | HTTP connectors. The AJP connectors do not support them.</b> |
||
| 11 | </p> |
||
| 12 | |||
| 13 | </div><h3 id="Asynchronous_writes">Asynchronous writes</h3><div class="text"> |
||
| 14 | |||
| 15 | <p> |
||
| 16 | When using HTTP connectors (based on APR or NIO/NIO2), |
||
| 17 | Tomcat supports using sendfile to send large static files. |
||
| 18 | These writes, as soon as the system load increases, will be performed |
||
| 19 | asynchronously in the most efficient way. Instead of sending a large response using |
||
| 20 | blocking writes, it is possible to write content to a static file, and write it |
||
| 21 | using a sendfile code. A caching valve could take advantage of this to cache the |
||
| 22 | response data in a file rather than store it in memory. Sendfile support is |
||
| 23 | available if the request attribute <code>org.apache.tomcat.sendfile.support</code> |
||
| 24 | is set to <code>Boolean.TRUE</code>. |
||
| 25 | </p> |
||
| 26 | |||
| 27 | <p> |
||
| 28 | Any servlet can instruct Tomcat to perform a sendfile call by setting the appropriate |
||
| 29 | request attributes. It is also necessary to correctly set the content length |
||
| 30 | for the response. When using sendfile, it is best to ensure that neither the |
||
| 31 | request or response have been wrapped, since as the response body will be sent later |
||
| 32 | by the connector itself, it cannot be filtered. Other than setting the 3 needed |
||
| 33 | request attributes, the servlet should not send any response data, but it may use |
||
| 34 | any method which will result in modifying the response header (like setting cookies). |
||
| 35 | </p> |
||
| 36 | |||
| 37 | <ul> |
||
| 38 | <li><code>org.apache.tomcat.sendfile.filename</code>: Canonical filename of the file which will be sent as |
||
| 39 | a String</li> |
||
| 40 | <li><code>org.apache.tomcat.sendfile.start</code>: Start offset as a Long</li> |
||
| 41 | <li><code>org.apache.tomcat.sendfile.end</code>: End offset as a Long</li> |
||
| 42 | </ul> |
||
| 43 | <p> |
||
| 44 | In addition to setting these parameters it is necessary to set the content-length header. |
||
| 45 | Tomcat will not do that for you, since you may have already written data to the output stream. |
||
| 46 | </p> |
||
| 47 | |||
| 48 | <p> |
||
| 49 | Note that the use of sendfile will disable any compression that Tomcat may |
||
| 50 | otherwise have performed on the response. |
||
| 51 | </p> |
||
| 52 | |||
| 53 | </div></div></div></div></div><footer><div id="footer"> |
||
| 54 | Copyright © 1999-2025, The Apache Software Foundation |
||
| 55 | <br> |
||
| 56 | Apache Tomcat, Tomcat, Apache, the Apache Tomcat logo and the Apache logo |
||
| 57 | are either registered trademarks or trademarks of the Apache Software |
||
| 58 | Foundation. |
||
| 59 | </div></footer></div></body></html> |