Proxy bug?

Question

I'm using Weblogic 5.1, cluster of 2 instances + proxy. Number of instances
          doesn't matter the issue occures even with one instance.
          Use some servlet/jsp which prints something to System.out to trace its work.
          In browser connect to server via proxy. Press refresh button. Press refresh
          button many times fast to reach the situation when you start new request
          before previous one is satisfied.
          Stop at some point.
          Proxy continues to send requests to server every 1-2 seconds. Even if you
          shut the server down and start it again the proxy continues to send
          requests. Only proxy restart resolves situation.
          You can request nonexisting file (and see message "resource not found")
          instead of servlet/jsp with the same results - proxy continues sending
          requests forever.
          I "succeeded" to make proxy sending request to both instances in cluster,
          but "unfortunately" didn't succeed to make it sending several different
          requests (requesting different files), only the first one is "lucky".
          Does anyone knows anything about this issue?
          Thank you,
          Vladimir Reznitsky.
          

Answer 1

Hi all,
          We have come across this and many other infinite loop problems in
          HttpClusterServlet WLS 5.1 SP6.
          This particular infinite loop has 2 flavours. One, in which both proxy and the
          clustered server are both
          looping. Second, which is triggered when the initial requets is interrupted before
          it gets relayed to
          the appropriate clustered server, puts the proxy in infinite loop spitting out
          errors like crazy.
          The circumstances under which these infinite loops are triggered are so simple and
          easy
          to duplicate that it is rediculous they were not caught in testing. If an infinite
          loop of
          both the proxy and a clustered WLS or even just the proxy is not in show-stopper
          category then you wonder what is?
          I have opened a case about these infinite loops with BEA support and yes , I got a
          reply
          from them telling me the patch the WebLogic source code (which I do not have)
          myself.
          I am looking forward to all of these infinite loop fixes pretty soon in form of
          Service Pack
          not source-code level instruction.
          -Andrew
          For fun, here is what BEA told me to do:
          Greetings ! I am providing some notes which will help you in providing a
          patch to your application which is resullting in a an infinite loop.
          Notes:1. Use connection time out to stop proxying if all servers in the
          list are deadso that we won't keep trying forever.
          2. When the postData is not null, do not try to re-read the data from
          inputstreamto advoid "Expected the content-length is 500, but receive -1"
          error.
          3. In case of the first server is dead and second server get the request
          andupdate itself as the primary, we should throw IOException("I am no
          longer the primaryfor this object") insteadof RecoverPostDataException.
          This will avoidthe infinite loop for trying the first server.
          4. Separate RecoverPostDataException from IOException catch block in the
          proxy()function to avoid another infinite loop situation.
          Please see if this works for you and let me know if you have further
          questions. Regarding the case # 202581, I am not dealing the case, but I
          can definitely help you in getting a solution for that also.
          Thanks & Regards
          Kumar Allamraju wrote:
          > I guess this was a known issue reported by several customers.
          > If this problem is a show stopper , pls follow-up with support & refer Issue #
          > CR034694
          >
          > --
          > Kumar
          >
          > Vladimir Reznitsky wrote:
          >
          > > I'm using Weblogic 5.1, cluster of 2 instances + proxy. Number of instances
          > > doesn't matter the issue occures even with one instance.
          > > Use some servlet/jsp which prints something to System.out to trace its work.
          > >
          > > In browser connect to server via proxy. Press refresh button. Press refresh
          > > button many times fast to reach the situation when you start new request
          > > before previous one is satisfied.
          > > Stop at some point.
          > >
          > > Proxy continues to send requests to server every 1-2 seconds. Even if you
          > > shut the server down and start it again the proxy continues to send
          > > requests. Only proxy restart resolves situation.
          > >
          > > You can request nonexisting file (and see message "resource not found")
          > > instead of servlet/jsp with the same results - proxy continues sending
          > > requests forever.
          > >
          > > I "succeeded" to make proxy sending request to both instances in cluster,
          > > but "unfortunately" didn't succeed to make it sending several different
          > > requests (requesting different files), only the first one is "lucky".
          > >
          > > Does anyone knows anything about this issue?
          > >
          > > Thank you,
          > > Vladimir Reznitsky.