[weld-dev] Race condition in HttpContextLifecycle requestInitialized

[Martin Kouba]

Hi Benjamin,

Dne 2.10.2016 v 11:36 Benjamin Confino napsal(a):
> Hello.
>
> We have a problem from a race condition in
> HttpContextLifecycle.requestInitialized()
>
> The condition is as follows:
>
> Thread one calls nestedInvocationGuard.set(*new*Counter());
> Thread two calls Counter counter = nestedInvocationGuard.get();  Object
> marker = request.getAttribute(GUARD_PARAMETER_NAME);
> Thread one has not yet called request.setAttribute(GUARD_PARAMETER_NAME,
> GUARD_PARAMETER_VALUE);

I don't understand how this could be a race condition? Are you saying 
that both these threads are processing a single request at the same time?

>
> This will result in thread two having a counter but no marker, leading
> to ServletLogger.LOG.guardLeak(counter.value);
>
> I believe this issue is known because of the following comment.
>
> * This request has not been processed yet but the guard is set already.
> That indicates, that the guard leaked from a previous request
> * processing - most likely the Servlet container did not invoke listener
> methods symmetrically. Log a warning and recover by
> * re-initializing the guard
>
> I am assuming that "symmetrically" is supposed to say "synchronised".

No it's not. It is really supposed to say symmetrically, it means that 
ServletRequestListener.requestInitialized(ServletRequestEvent) should be 
always followed by 
ServletRequestListener.requestDestroyed(ServletRequestEvent)?

>
> I have checked with the relevant team and there is no way we can call
> that method from inside a synchronised block. So I was hoping that you
> might have some alternatives?
>
> I noticed that the file at
> https://github.com/doctau/weld-core/blob/master/impl/src/main/java/org/jboss/weld/servlet/HttpContextLifecycle.javahas
> been updated and no longer has that race condition? Do you think
> including that update resolve this issue? And if so which release will
> include that update.

What version of Weld are you using?
What "update" do you have in mind?

>
> Regards
> Benjamin
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-- 
Martin Kouba
Software Engineer
Red Hat, Czech Republic