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POServlet 3 Async task on Tomcat 7
 

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    <p>I'm trying to implement Simple chat using Servlet 3.0 and Comet pattern based on its async support.</p> <p>I'm inspired by this article: <a href="http://www.javaworld.com/javaworld/jw-02-2009/jw-02-servlet3.html?page=3" rel="noreferrer">http://www.javaworld.com/javaworld/jw-02-2009/jw-02-servlet3.html?page=3</a></p> <p>My servlet looks like this.</p> <pre><code>@WebServlet(name="chatServlet", urlPatterns={"/ChatServlet"}, asyncSupported=true) public class ChatServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { AsyncContext aCtx = request.startAsync(request, response); ServletContext appScope = request.getServletContext(); List&lt;AsyncContext&gt; watchers = (List&lt;AsyncContext&gt;) appScope.getAttribute("watchers"); watchers.add(aCtx); //register the watcher } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { AsyncContext aCtx = request.startAsync(request, response); ServletContext appScope = request.getServletContext(); Queue&lt;String&gt; messages = (Queue&lt;String&gt;)appScope.getAttribute("messages"); messages.add(someMessage); } } </code></pre> <p>now my Listener looks like this:</p> <pre><code>@WebListener public class ChatPushService implements ServletContextListener { @Override public void contextInitialized(ServletContextEvent sce) { final List&lt;AsyncContext&gt; watchers = new ArrayList&lt;AsyncContext&gt;(); sce.getServletContext().setAttribute("watchers", watchers); // store new messages not published yet Queue&lt;String&gt; messages = new ConcurrentLinkedQueue&lt;String&gt;(); sce.getServletContext().setAttribute("messages", messages); Executor messageExecutor = Executors.newCachedThreadPool(); final Executor watcherExecutor = Executors.newCachedThreadPool(); while(true) { if(!messages.isEmpty()) { System.out.println("notEmpty"); String message = messages.poll(); messageExecutor.execute(new Runnable(){ @Override public void run() { for(final AsyncContext aCtx : watchers){ watcherExecutor.execute(new Runnable(){ @Override public void run() { try { aCtx.getResponse().getWriter().print("brrrrr"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }); } } }); } } } } </code></pre> <p>When I'm starting my it's freezing during container initiation.</p> <pre><code>Nov 1, 2011 1:12:09 AM org.apache.catalina.core.AprLifecycleListener init INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/lib/jvm/java-6-openjdk/jre/lib/amd64/server:/usr/lib/jvm/java-6-openjdk/jre/lib/amd64:/usr/lib/jvm/java-6-openjdk/jre/../lib/amd64:/usr/java/packages/lib/amd64:/usr/lib/jni:/lib:/usr/lib Nov 1, 2011 1:12:09 AM org.apache.tomcat.util.digester.SetPropertiesRule begin WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:Servlet3Comet' did not find a matching property. Nov 1, 2011 1:12:09 AM org.apache.coyote.AbstractProtocol init INFO: Initializing ProtocolHandler ["http-bio-8080"] Nov 1, 2011 1:12:09 AM org.apache.coyote.AbstractProtocol init INFO: Initializing ProtocolHandler ["ajp-bio-8009"] Nov 1, 2011 1:12:09 AM org.apache.catalina.startup.Catalina load INFO: Initialization processed in 624 ms Nov 1, 2011 1:12:09 AM org.apache.catalina.core.StandardService startInternal INFO: Starting service Catalina Nov 1, 2011 1:12:09 AM org.apache.catalina.core.StandardEngine startInternal INFO: Starting Servlet Engine: Apache Tomcat/7.0.22 </code></pre> <p>It looks like <code>public void contextInitialized</code> function is not running asynchronously on background and is blocking further container initialization. </p> <p>Why? </p> <p>can anybody help me on this issue? </p>
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