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Thread: Synchronization of ServletContext Object

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    Default Synchronization of ServletContext Object

    Hi All,

    -- I am trying to make the ServletContext synchronize because when 2 or more clients, are trying to modify the same servletcontext attributes, then that will be a problem. Because Servlet A tries to set context attribute as context.setAttribute("A","test1"); and Servlet B tries to set context attribute as context.setAttribute("A","B related code"); It could happen because Servlet B doesn't know that Servlet A also has the same attribute. That will be a problem as now servlet A will get the output as "B related Code" instead of "test1" if both acces the same code at a time, and Servlet B changes before servlet A recieves the response

    --If clientA write synchronize(getServletContext()) and in that he sets 2 attributes context.set("A","test1") and context.set("B", "test2"), clientA first gets the lock on the ServletContext object.

    --But another person (clientB) from another servlet also try to access the synchronize(getServletContext()) method and try to replace the values of the attributes "A" and "B" when clientA's lock is still there. Will clientB can access it...? I think no, because clientA has already lock.

    -- Now my question is, will clientB will able to run his Servlet or any other client can run their servlets, on the same context , as clientA has already a lock on contextobject. And for the servlet to run, the servlet should be on running on that context itself and since the lock has already been obtained for that context, how can other client requests be servered for anyting ( I meant not only for the attributes but any other code in it), until clientA releases the lock ?

    NOTE: I think that getServletContext() will return the same context reference always instead of creating with the "new" operator each time. i.e, singleton object.

    Please clarify me regarding this..!


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    Default Re: Synchronization of ServletContext Object

    Hi jkoder70014,

    Your concern about ServletContext's thread-safe is right.

    Now my question is, will clientB will able to run his Servlet or any other client can run their servlets, on the same context , as clientA has already a lock on contextobject. And for the servlet to run, the servlet should be on running on that context itself and since the lock has already been obtained for that context, how can other client requests be servered for anyting ( I meant not only for the attributes but any other code in it), until clientA releases the lock ?
    Client B is still able to run his Serlvet, and his Servlet code must wait for other threads release the lock on ServletContext object. Just wait until it owns the lock on ServletContext.

    immutable objects
    Last edited by ha.minh.nam; December 4th, 2011 at 07:30 PM.

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    Talking Re: Synchronization of ServletContext Object

    i will recommend you to use HttpSession object instead for context objects to set attributes and the server will take care of all the things you are thinking for .
    servlet context is a shareable scope which is shared among servlets and sessions are user specific and will help you in your case.
    and this is what i used in my webApp.

    regards
    Last edited by arvindbis; August 23rd, 2011 at 12:02 PM.

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