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    <p>To start, I wouldn't use JSP for this. There it is not for.</p> <p>When you're on Java EE 5, use the container-provided jobscheduling APIs for this. Further detail depends on the container you're using. JBoss AS 5 for example ships with Quartz out the box. Or when you're using a framework on top of JSP/Servlet which offers jobscheduling APIs, like as <a href="http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/scheduling.html" rel="nofollow noreferrer">Spring</a>, then you should use it.</p> <p>If there are none (e.g. you're using just Tomcat 6), or you want to be independent from the container and/or framework, create a <a href="http://java.sun.com/javaee/5/docs/api/javax/servlet/ServletContextListener.html" rel="nofollow noreferrer"><code>ServletContextListener</code></a> with a <a href="http://java.sun.com/javase/6/docs/api/java/util/concurrent/ScheduledExecutorService.html" rel="nofollow noreferrer"><code>ScheduledExecutorService</code></a>. Further detail can be found in <a href="https://stackoverflow.com/questions/4691132/how-to-keep-the-servlet-continously-running/4691650#4691650">this answer</a>.</p> <p>Or when you're already on a Java EE 6 container which supports EJB 3.1 (JBoss AS 6, GlassFish 3, but thus <em>not</em> Tomcat 7), easiest is to create a <a href="http://download.oracle.com/javaee/6/api/javax/ejb/Singleton.html" rel="nofollow noreferrer"><code>@Singleton</code></a> EJB with <a href="http://download.oracle.com/javaee/6/api/javax/ejb/Schedule.html" rel="nofollow noreferrer"><code>@Schedule</code></a> method.</p> <pre><code>@Singleton public class UpdateSubscriptions { @Schedule(hour="*/6", minute="0", second="0", persistent=false) public void run() { // Do your job here. } } </code></pre> <p>That's it. No further configuration is necessary.</p> <hr> <p><strong>Update</strong>: as per the comments, you're using Tomcat (6 or 7?). To start a thread during webapp's startup which runs the task every 6 hours, use the example as provided in the <a href="https://stackoverflow.com/questions/4691132/how-to-keep-the-servlet-continously-running/4691650#4691650">beforelinked answer</a> and make the following change in the <a href="http://download.oracle.com/javase/6/docs/api/java/util/concurrent/ScheduledExecutorService.html#scheduleAtFixedRate%28java.lang.Runnable,%20long,%20long,%20java.util.concurrent.TimeUnit%29" rel="nofollow noreferrer"><code>scheduleAtFixedRate()</code></a> method</p> <pre><code>scheduler.scheduleAtFixedRate(new UpdateSubscriptions(), 0, 6, TimeUnit.HOURS); </code></pre> <p>The class <code>UpdateSubscriptions</code> must implement <a href="http://download.oracle.com/javase/6/docs/api/java/lang/Runnable.html" rel="nofollow noreferrer"><code>Runnable</code></a> and the actual job needs to be done in the <a href="http://download.oracle.com/javase/6/docs/api/java/lang/Runnable.html#run%28%29" rel="nofollow noreferrer"><code>run()</code></a> method which you <a href="http://download.oracle.com/javase/6/docs/api/java/lang/Override.html" rel="nofollow noreferrer"><code>@Override</code></a>, like as in the example in the linked answer.</p>
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    1. POBackground timer task in JSP/Servlet web application
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    1. POBackground timer task in JSP/Servlet web application
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    1. CO+1 can't get an answer any perfect than this.
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    2. COI am using Tomcat only. I saw the linked answer too. 1. I intended to use it in a class, was crntlt not going to use JSP. But, is servlet a better way? 2. if i put it in a servlet as shown in linked answer won't it create new thread every 6 hours?
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    3. COIt's not a servlet. It's a listener. And there's only one instance of it in webapp's lifetime (the same applies to servlets by the way).
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