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POExecutorService in Java Servlet
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copied!<p>I need to perform some tasks(Mostly Call multiple External URL's with request parameters and read data) concurrently in java servlet and send response to user within a few seconds.I am trying to use ExecutorService to achieve the same. I need four FutureTasks created in each user request in the doGet method. Each Task runs for around 5-10 sec and the total response time to the user is around 15 sec.</p> <p>Can you please suggest which of the following design is better while using ExecutorService in a Java servlet?</p> <p><strong>1)(Creating newFixedThreadPool per request and shutting it down ASAP)</strong></p> <pre><code>public class MyTestServlet extends HttpServlet { ExecutorService myThreadPool = null; public void init() { super.init(); } protected void doGet(HttpServletRequest request,HttpServletResponse response) { myThreadPool = Executors.newFixedThreadPool(4); taskOne = myThreadPool.submit(); taskTwo = myThreadPool.submit(); taskThree = myThreadPool.submit(); taskFour = myThreadPool.submit(); ... ... taskOne.get(); taskTwo.get(); taskThree.get(); taskFour.get(); ... myThreadPool.shutdown(); } public void destroy() { super.destroy(); } } </code></pre> <p><strong>2) (Creating newFixedThreadPool during Servlet Init and shutting it down on servlet destroy)</strong></p> <pre><code>public class MyTestServlet extends HttpServlet { ExecutorService myThreadPool = null; public void init() { super.init(); //What should be the value of fixed thread pool so that it can handle multiple user requests without wait??? myThreadPool = Executors.newFixedThreadPool(20); } protected void doGet(HttpServletRequest request,HttpServletResponse response) { taskOne = myThreadPool.submit(); taskTwo = myThreadPool.submit(); taskThree = myThreadPool.submit(); taskFour = myThreadPool.submit(); ... ... taskOne.get(); taskTwo.get(); taskThree.get(); taskFour.get(); ... } public void destroy() { super.destroy(); myThreadPool.shutdown(); } } </code></pre> <p><strong>3) (Creating newCachedThreadPool during Servlet Init and shutting it down on servlet destroy)</strong></p> <pre><code>public class MyTestServlet extends HttpServlet { ExecutorService myThreadPool = null; public void init() { super.init(); myThreadPool = Executors.newCachedThreadPool(); } protected void doGet(HttpServletRequest request,HttpServletResponse response) { taskOne = myThreadPool.submit(); taskTwo = myThreadPool.submit(); taskThree = myThreadPool.submit(); taskFour = myThreadPool.submit(); ... ... taskOne.get(); taskTwo.get(); taskThree.get(); taskFour.get(); ... } public void destroy() { super.destroy(); myThreadPool.shutdown(); } } </code></pre>

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