java.lang.ClassCastException in Jetty when using Spring Session

[johanhaleby]

I'm using Jetty 9.4.12 to which I deploy a Spring application using Spring Session with Redis. The application exposes a server-sent event (SSE) endpoint configured by Spring. But I seem to run into an issue when the javascript SSE client connection times out. I see the following log produced by Jetty:

[WARNING] java.lang.ClassCastException: org.springframework.session.web.http.SessionRepositoryFilter$SessionRepositoryRequestWrapper$HttpSessionWrapper 
    cannot be cast to org.eclipse.jetty.server.session.SessionHandler$SessionIf 
    while invoking onComplete listener org.eclipse.jetty.server.session.SessionHandler$SessionAsyncListener@67e50aa3

I.e. the cast made in SessionAsyncListener fails.

Is this a bug in Jetty? Is it correct to always assume that session is an instance of SessionIf? It doesn't seem to be the case for me at least.

For context I've also posted this as a question on Stackoverflow.

[joakime]

SessionAsyncListener code ...

https://github.com/eclipse/jetty.project/blob/bc1e58b0f591311b5909029c13b0b5d620a18d49/jetty-server/src/main/java/org/eclipse/jetty/server/session/SessionHandler.java#L170-L174

[joakime]

Do you have the complete stacktrace?

[johanhaleby]

Jetty just logs the last line and I've struggled to change this but I've not yet succeeded. However I've managed to connect a debugger and calling exception.getStackTrace() gives me the following:

{java.lang.StackTraceElement[11]@17832} 
 0 = {java.lang.StackTraceElement@17833} "org.eclipse.jetty.server.session.SessionHandler.complete(SessionHandler.java:366)"
 1 = {java.lang.StackTraceElement@17834} "org.eclipse.jetty.server.session.SessionHandler$SessionAsyncListener.onComplete(SessionHandler.java:173)"
 2 = {java.lang.StackTraceElement@17835} "org.eclipse.jetty.server.HttpChannelState$4.run(HttpChannelState.java:889)"
 3 = {java.lang.StackTraceElement@17836} "org.eclipse.jetty.server.handler.ContextHandler.handle(ContextHandler.java:1431)"
 4 = {java.lang.StackTraceElement@17837} "org.eclipse.jetty.server.HttpChannelState.runInContext(HttpChannelState.java:1116)"
 5 = {java.lang.StackTraceElement@17838} "org.eclipse.jetty.server.HttpChannelState.onComplete(HttpChannelState.java:905)"
 6 = {java.lang.StackTraceElement@17839} "org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:508)"
 7 = {java.lang.StackTraceElement@17840} "org.eclipse.jetty.server.HttpChannel.run(HttpChannel.java:305)"
 8 = {java.lang.StackTraceElement@17841} "org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:765)"
 9 = {java.lang.StackTraceElement@17842} "org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:683)"
 10 = {java.lang.StackTraceElement@17843} "java.lang.Thread.run(Thread.java:748)"

[gregw]

I think it is kind of strange and fragile to wrap the session object.... But obviously it is done. We can use our Request.getBaseRequest method to navigate to the unwrapped request and get the unwrapped session from it.

[johanhaleby]

@gregw

Do you mean that instead of doing this?

complete(((HttpServletRequest)event.getAsyncContext().getRequest()).getSession(false));

we could do:

HttpSession session = ((HttpServletRequest)event.getAsyncContext().getRequest()).getSession(false)
complete(Request.getBaseRequest(session));

Or do you mean instead of the cast inside SessionHandler?

Btw, is this warning something that we could ignore for now? Or will this produce resource leaks or something that will accumulate over time?

[gregw]

I was thinking:

complete(Request.getBaseRequest(event.getAsyncContext().getRequest()).getSession(false));

Depending on what session store you are using, the warnings are probably not good and could mean that sessions are not being passivated correctly.

We have a release due this week... so @janbartel can you fix (assuming the fix is OK?) this before that?

[janbartel]

Fixed for 9.4.13.

[joakime]

Jetty version 9.4.13.v20181111 is now available on Maven Central.

[johanhaleby]

@joakime Awesome!

Thanks for your help.