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Build Identifier: 20100917-0705 I use Jetty as my embedded web server in my application. And I have a function to restart the Jetty dynamically in my application. I just use the org.eclipse.jetty.server.Server.start() to start a web server and org.eclipse.jetty.server.Server.stop() to stop a web server. The problem is I have DWR in my web application and when restart the Jetty, DWR will throw an exception as below. It seems the Jetty didn’t unload all loaded classes or didn’t stop running threads when Jetty stopped. So that the restart will cause the problem but the first start is ok. ---------- 2011/2/17 PM 05:18:59 org.directwebremoting.impl.DefaultServerContextBuilder get severe: Error initializing ServerContext because this is not a DWR thread and there is more than one DWR servlet in the current classloader. 2011/2/17 PM 05:18:59 org.directwebremoting.impl.DefaultServerContextBuilder get severe: This probably means that either DWR has not been properly initialized (in which case you should delay the current action until it has) 2011/2/17 PM 05:18:59 org.directwebremoting.impl.DefaultServerContextBuilder get severe: or that there is more than 1 DWR servlet is configured in this classloader, in which case you should provide a ServletContext to the get() yourself. 2011-02-17 17:18:59.450:WARN::/center/ppbe.json java.lang.IllegalStateException: No singleton ServerContext see logs for possible causes and solutions. at org.directwebremoting.impl.DefaultServerContextBuilder.get(DefaultServerContextBuilder.java:46) at org.directwebremoting.impl.DefaultServerContextBuilder.get(DefaultServerContextBuilder.java:29) at org.directwebremoting.extend.Factory.get(Factory.java:60) at org.directwebremoting.ServerContextFactory.get(ServerContextFactory.java:35) at com.cyberpowersystems.ppbe.center.core.facility.FacilityUpdater.getScriptSession(FacilityUpdater.java:293) at com.cyberpowersystems.ppbe.center.core.facility.FacilityUpdater.isScriptSessionViewSnapExist(FacilityUpdater.java:265) at com.cyberpowersystems.ppbe.center.core.jsonservice.handler.DevicePresentHandler.handle(DevicePresentHandler.java:29) at com.cyberpowersystems.ppbe.center.core.jsonservice.RequestProcessor.process(RequestProcessor.java:73) at com.cyberpowersystems.ppbe.center.ui.web.jsonservice.JsonServiceServlet.doPost(JsonServiceServlet.java:66) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at javax.servlet.http.HttpServlet.service(HttpServlet.java:820) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:527) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1216) at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:176) at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:145) at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:92) at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:381) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1187) at com.cyberpowersystems.ppbe.center.ui.web.processor.PathFilter.processUrlRequest(PathFilter.java:171) at com.cyberpowersystems.ppbe.center.ui.web.processor.PathFilter.doFilter(PathFilter.java:85) at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1187) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:421) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:493) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:225) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:930) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:358) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:183) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:866) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:245) at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:126) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:113) at org.eclipse.jetty.server.Server.handle(Server.java:351) at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.java:594) at org.eclipse.jetty.server.HttpConnection$RequestHandler.content(HttpConnection.java:1059) at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:764) at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:217) at org.eclipse.jetty.server.HttpConnection.handle(HttpConnection.java:424) at org.eclipse.jetty.server.bio.SocketConnector$ConnectorEndPoint.run(SocketConnector.java:241) at org.eclipse.jetty.server.ssl.SslSocketConnector$SslConnectorEndPoint.run(SslSocketConnector.java:645) at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:436) at java.lang.Thread.run(Unknown Source) Reproducible: Always Steps to Reproduce: 1. embedded Jetty in Java 2. add DWR in WAR 3. dynamically restart Jetty
The problem is solved by DWR, ref: http://directwebremoting.org/jira/browse/DWR-498 See if the Jetty need to handle static variable or not when restart?
Jetty did have a couple of references holding old classloaders in memory. These have been fixed in latest jetty 7.3 releases, so if DWR is loaded from the WEB-INF/lib directory, then the loaded class should be correctly discarded when the context is stopped. But I don't think this could have been your problem. Note that if you load DWR from the system classpath, then you may need to manage the statics yourself - perhaps in the destroy methods. Where were you loading DWR from? if it was from WEB-INF/lib and the static was set after a restart, then please reopen this issue and we'll look more closely.
