6 Replies Latest reply on Nov 15, 2010 4:54 AM by Mike Wigge

    Problem with more than 10 parallel connections in JBoss5.1

    Mike Wigge Newbie

      Hello

       

      I've got a problem with more than 10 parallel connections. We are using an Apache as a proxy server and a JBoss5.1 instance as our application server We use Apache mod_rewrite. mod_ajp is not used. Today we did a loadtest to check the systems performance. While we were increasing the amount of users on the application server we realized that there is a limitation of ~10 parallel users. (apache reports 503 Service Temporarily unavailable) There are no exceptions in the LogFile of the JBoss (even in DEBUG). We already increased the maxThreads in jboss-service.xml from 10 to 100, still facing this connection limitation.

       

      we already searched the community forum (keywords: Jboss5, parallel connections, acceptCount, maxThread, limit) but got no idea on how to solve our issue.

       

      does someone know which configuratioin parameter could cause this limitation or give us a hint concerning our search keywords.

       

      best regards,

       

      mike

        • 1. Re: Problem with more than 10 parallel connections in JBoss5.1
          Wolfgang Knauf Master

          Hi,

           

          what OS do you use? Do you use Windows Vista or similar? This OS limits parallel connections. I don't know the exact value, but it might be "10".

           

          The server versions don't have this limit.

           

          Best regards

           

          Wolfgang

          • 2. Re: Problem with more than 10 parallel connections in JBoss5.1
            Mike Wigge Newbie

            Hi Wolfgang ,

             

            thanks for your reply. We are using Suse Linux Enterprise Server 10. Do you know if there is a limitation on that OS too?

             

            Regards

            Mike

            • 3. Re: Problem with more than 10 parallel connections in JBoss5.1
              Wolfgang Knauf Master

              I don't think that Suse has this built in limitation, too ;-).

               

              But it seems the "iptables" command allows setting some limits (I don't know details, just found this snippet by asking a popular search engine)::

               

              man iptables

              ...

              connlimit

              Allows  you  to restrict the number of parallel connections to a server per client IP address

              (or client address block).

               

              [!] --connlimit-above n

               

              Match if the number of existing connections is (not) above n.

               

               

              --connlimit-mask prefix_length

               

              Group hosts using the prefix length. For IPv4, this  must  be  a

               

              number  between  (including)  0  and 32. For IPv6, between 0 and

               

              128.

               

               

              Examples:

               

               

              # allow 2 telnet connections per client host

               

              iptables  -A  INPUT  -p  tcp  --syn  --dport  23  -m   connlimit

               

              --connlimit-above 2 -j REJECT

              • 4. Re: Problem with more than 10 parallel connections in JBoss5.1
                Mike Wigge Newbie

                Hello Wolfgang,

                 

                thanks for your help! Now we are sure that this limitation is not caused by the OS. The Apache gets requests and trys to connect to the JBoss which sends no response. The communication between user and Apache works fine but the communication between Apache and JBoss just works with about 10 parallel connections.

                 

                Would be great if someone's got another idea.

                 

                Thanks in advance.

                 

                Best regards

                Mike

                • 5. Re: Problem with more than 10 parallel connections in JBoss5.1
                  Peter Johnson Master
                  Do you use Windows Vista or similar? This OS limits parallel connections. I don't know the exact value, but it might be "10".

                  Actually, the limitation of incomming connections (10) for desktop versions of Windows is a EULA limitation. As far as I know, only Miscrosoft-written server products (IIS, SQL Server, etc.) enforce this limit. I ran across this enforcement once when trying to run some JMeter scripts against an ASP.NET site. However, no Java app servers that I know of enforce this limitation, nor does Apache HTTPD enforce this.

                   

                  Legally, you are violating the desktop Windows EULA if you allow more than 10 incoming connections. But I doubt that in a dev/test/home environment that anyone (i.e. Microsoft) will care. But for production unless you can guarantee 10 or fewer connections (small office?), then you had best be using one of the server versions of Windows which have no limits in their EULAs.

                   

                  (Sorry for this side track. We now return you to the originally scheduled forum post...)

                  • 6. Re: Problem with more than 10 parallel connections in JBoss5.1
                    Mike Wigge Newbie

                    We figured out that our Apache limits our TPS. There is no user limitation. If we are using the JBoss without the Apache we've got ~11000 TPS. Thanks for your help! Now I've to ask in the Apache forum

                     

                    Mike