Further to my conversation in Weld forum, https://developer.jboss.org/thread/257300, I think the scope contexts such as RequestContext, SessionContext should be propagated to a different thread on the async call scenarios. The threadlocal contexts have introduced a lot of servlet work, which potentially violates servlet specification. Even now, Tomcat is still having some issues (http://weld.cdi-spec.org/documentation/#8). Can we start thinking about this and get this addressed so that the application servers can get the async handled free?