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  1. Struts 2
  2. WW-3957

Multiple concurrent AJAX requests can collide

    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 2.3.8
    • Fix Version/s: 2.5.8
    • Component/s: Plugin - Portlet
    • Labels:
      None
    • Environment:

      Liferay/Tomcat

      Description

      If there are multiple AJAX request in the same time (and same HTTP Session) they can somehow overwrite the concurrent thread's data (for example the result location).

      Update:
      There is no conflict when we use resource URL, but when we use the action URL the struts2 portlet plugin executes the interceptor stack twice:

      • First in Action phase: This runs normally the action, and saves the full stack and response location to the http session. The PortletStateInterceptor saves the stack, the PortletResult saves the location.
      • Second in Render phase: This phase restores the value stack and runs a dummy action (DirectRenderFromEventAction) which does noting but returns the previously saved response location from the session.

      The problem is that key for the http session objects is a constant (Location: RENDER_DIRECT_LOCATION, Valuestack: STACK_FROM_EVENT_PHASE).

      Let's see an example, when there are two concurrent thread A,B:
      1. A action phase (saves locationA to session(RENDER_DIRECT_LOCATION), saves stackA to session(STACK_FROM_EVENT_PHASE))
      2. B action phase (saves locationB to session(RENDER_DIRECT_LOCATION), saves stackB to session(STACK_FROM_EVENT_PHASE), so it overwrites locationA, stackA!)
      3. A render phase (loads stackB, locationB from session. Returns/forwards to locationB) So it returns the response of the B thread too!
      4. B render phase (loads stackB, locationB from session. Returns/forwards to locationB)

      Possible solution is to add the threadId to the session key (RENDER_DIRECT_LOCATION + ThreadId). This could cause a massive load to the session so some clever clean up needed.

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              • Assignee:
                Unassigned
                Reporter:
                idonat Donat Iszak
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                • Created:
                  Updated:
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