Verified in rhevm-3.3.1-0.47.el6ev.noarch (is34). Verified by automation (using Selenium). I spun up 4 Firefox browsers in parallel and each one performed login & logout on User Portal 20 times in a row. All login/logout actions eneded up well, no problems were encountered.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHBA-2014-0227.html