Intermittent NullPointerException, Errai 2.1.1.Final

[nva]

I'm getting a lot of the following errors in the jetty (jetty8 on Ubuntu) error logs. When this happens the bus communication seems to 'hang':

2013-05-21 05:24:12.352:WARN:oejs.ServletHandler:/dtt/in.77802-39353.erraiBus
java.lang.NullPointerException
        at org.jboss.errai.bus.server.HttpSessionProvider$HttpSessionWrapper.<init>(HttpSessionProvider.java:89)
        at org.jboss.errai.bus.server.HttpSessionProvider$SessionsContainer.createSession(HttpSessionProvider.java:63)
        at org.jboss.errai.bus.server.HttpSessionProvider.createOrGetSession(HttpSessionProvider.java:51)
        at org.jboss.errai.bus.server.HttpSessionProvider.createOrGetSession(HttpSessionProvider.java:39)
        at org.jboss.errai.bus.server.servlet.DefaultBlockingServlet.doGet(DefaultBlockingServlet.java:97)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:598)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:486)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119)
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:524)
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:233)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1065)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:413)
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:192)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:999)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117)
        at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:250)
        at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:149)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:111)

        at org.eclipse.jetty.server.Server.handle(Server.java:350)
        at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:454)
        at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:890)
        at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:944)
        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:630)
        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:230)
        at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:77)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:606)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:46)
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:603)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:538)
        at java.lang.Thread.run(Thread.java:722)

It appears that the system recovers from this after a while and later the exception happens again. Any suggestions on what could be done to find the root cause and fix the problem?

An Errai upgrade is not an option in this project, unfortunately. We're using generics in the portable classes and there is bug for which the fix - as discussed previously - is planned for Errai 3.0 only.

Thanks!

Cheers,

V.

[edewit]

Hi Valentin,

What I can see from the code is that either httpSessionId or the remoteQueueID are null the session gets created int eh default blocking servlet so it's Id can't be null so that leaves the remoteQueueID but that should have been created by the client and put in the http header. Can you verify that this RemoteQueueID is in the http headers for the bus request?

Cheers,

     Erik Jan

[jfuerth]

Hi Valentin,

We've just resolved a major issue on the 2.3.x branch (ERRAI-553), and we're now planning to do another release with that fix. Can you remind us the JIRA issue number associated with your generics issue? Maybe we can pull in that fix so upgrading to 2.3.1 will be an option for you after all...

-Jonathan

[nva]

Hi Jonathan,

thanks - to be honest, I didn't look into Jira, the issue was raised by someone else initially. It's this thread: https://community.jboss.org/thread/223072?tstart=0

Cheers,

V.

[jfuerth]

Based on the information in that thread, I believe this generics problem is already fixed in 2.3.0.Final. It seems that the issue with 2.3.0 was that you had dependency problems and were unable to compile your project against Errai 2.3.0.Final + GWT 2.4.0.

Can you try again? If we get the feedback soon enough, and there is still a generics problem with Errai Marshalling, we'd like to include the fix in 2.3.1.Final.

Best,

Jonathan

[nva]

Hi Jonathan,

thanks, our upgrade to GWT 2.5 is not trivial in this project. We use GWTP and there are issues with it under GWT 2.5. Will try to verify the generics issue in a unit test asap, though.

Cheers,

V.

[nva]

Ok, I got the project to compile on GWT 2.5 - well to the point where it complains about the generics in the portable class. Will put the details onto the relevant thread.

Cheers,

V.