How can I have my servlet accept 100 concurrent client requests?

Question

          My servlet extends HttpServlet so it is multithreaded. Then I have written a java
          client which starts 100 concurrent threads that try to contact the servlet.
          There are always lots of threads which are refused by the Weblogic Server 6.0.
          They get a 'Connection refused' exception. Sometimes there are 50 refused connections,
          sometimes there are 0 refused connections (not very often), sometimes there are
          80 refused connections (usually).
          I have checked the 'Servlet' documentation and the 'J2EE Design Considerations
          for Weblogic Server' which recommends not to exceede the execute thread count
          number of 15. I have not changed that value, I do not even know if it still exists
          in Weblogic 6.0 as the document refers to the 5.0 version.
          Does anybody know how to solve this problem? How can I have the client requests
          waiting rather than being refused? Of course the main goal is to serve all the
          client requests, not to refuse.
          This is the code that the client thread uses to contact the servlet:
          URL url = new URL("http://localhost:7001/examplesWebApp/myServlet");
          URLConnection conn = url.openConnection();
          conn.setDoInput(true);
          conn.setDoOutput(true);
          DataOutputStream os = new DataOutputStream(conn.getOutputStream());
          os.writeBytes()
          os.writeBytes()
          Thanks for your time,
          David
          

Answer 1

          The key is
          KKEY_LOCALMACHINE\SYSTEM\CurrentControlSet\Services\TCPIP\Parameters
          There you may need add a value "MaxUserPort" as REG_DWORD (5000 is default), also
          change "TcpTimedWaitDelay" to small number (30 is minimum). You may have trouble
          to find them. Just add them.
          You can also use Microsoft Web Application Stress Tool to test your Weblogic applications.
          As a free test tool, it is really powerful, although not so flexible.
          I guess you write your own test tool with java.net.URLConnection. I am not sure
          about the power of this class. In my case, I wrote my stress test tools with Java
          Socket. I can test application on Weblogic 6 with 1000 threads with my own tool
          and Microsoft tool, depending on memory and CPU of the machines I use. I run my
          tests on both Windows 2000 professional and Solaris.
          Check your CPU and memory usage with task manager.
          On the other hand, you should check log message on Weblogic 6. Try to turn on
          HTTP debug by add the following in your config.xml in tag <Server>.
          <ServerDebug DebugHttp="true" DebugURLResolution="true"
          JDBCConn="true" JDBCSQL="true" ListenThreadDebug="true" Name="myserver"/>
          "David Ruana" <[email protected]> wrote:
          >
          >Xiang, I really appreciate your help. I changed my Weblogic server configuration
          >from the console but I still experience the same problems.
          >
          >I start my 100 threads, and from about the 20th onward all them get the
          >'Connection
          >refused' exception in the URLConnection::getOutputStream() function,
          >always after
          >a successful URLConnection::openConnetion().
          >
          >My system is Windows 2000 Professional (Spanish version). I tried to
          >check the
          >open client socket descriptor limit but I was not able to find the TCPIP/MAXUSERPORT
          >in the registry. Do you know how is this entry called in Windows 2000?
          >
          >At this point I am not sure whether my problems are related to the Weblogic
          >server
          >or to the operative system. I will keep trying... I would appreciate
          >any other
          >suggestion.
          >
          >Thank you very much.
          >
          >
          >
          >"Xiang Rao" <[email protected]> wrote:
          >>
          >>It is better to use Weblogic 6 console to configure Weblogic server.
          >>In the console,
          >>there is tab Servers->myServer->Congiguration->Tuning, you can find
          >execute
          >>length
          >>and backlog.
          >>
          >>If you use Windows as test client, note Windows have a 5000 open client
          >>socket
          >>descriptors limit. You need change Windows Registry (TCPIP/MAXUSERPORT)
          >>to change
          >>this parameter.
          >>
          >>On the other hand, during test, you should monitor your test via Weblogic
          >>console
          >>(myServer->Monitoring->Performance), here you can see the change of
          >wait
          >>queue.
          >>If the queue keeps increaing, you are in trouble.
          >>
          >>Since you know how to use MBean, try to write customized (servlet, for
          >>example)
          >>to collect the following data: opened socket number, open socket number,
          >>opened
          >>session number and open session number. The two "open" numbers will
          >give
          >>you some
          >>clue. Also record your CPU and memory usage.
          >>
          >>BTW, what is the output you get from your test in terms of number of
          >>requests
          >>per second, response time and number of bytes downloaded/uplodaed per
          >>second?
          >>Are your test client and Weblogic running on the same machine?
          >>
          >>
          >>
          >>"David Ruana" <[email protected]> wrote:
          >>>
          >>>By the way, this is a piece of the config.xml file where you can see
          >>>my Server
          >>>configuration. It is the configuration which is installed in the examplesServer
          >>>in the free evaluation of Weblogic 6.0. I only modified the AcceptBacklog
          >>>value,
          >>>and added the ThreadPoolSize="15" line which was missing (I copied
          >from
          >>>the petstoreServer).
          >>>
          >>> <Server AcceptBacklog="1000" AdministrationPort="0" ClusterWeight="1"
          >>> ConsoleInputEnabled="false" DGCIdlePeriodsUntilTimeout="2"
          >>> DefaultProtocol="t3" DefaultSecureProtocol="t3s"
          >>> HttpdEnabled="true" JavaCompiler="C:\bea\jdk130/bin/javac"
          >>> ListenPort="7001" Name="examplesServer" NativeIOEnabled="true"
          >>>     ThreadPoolSize="15"
          >>> SocketReaderTimeoutMaxMillis="10"
          >>> TransactionLogFilePrefix="config/examples/logs/"
          >>> TunnelingClientPingSecs="45" TunnelingClientTimeoutSecs="40"
          >>>XMLRegistry="examplesXMLRegistry">
          >>> <ServerDebug Name="examplesServer"/>
          >>> <WebServer DefaultWebApp="DefaultWebApp_examplesServer"
          >>> LogFileName="./config/examples/logs/access.log"
          >>> LoggingEnabled="true" Name="examplesServer"/>
          >>> <Log FileName="./config/examples/logs/weblogic.log" Name="examplesServer"/>
          >>> <KernelDebug Name="examplesServer"/>
          >>> <SSL Enabled="true" ListenPort="7002" Name="examplesServer"
          >>> PeerValidationEnforced="0"
          >>> ServerCertificateChainFileName="./config/examples/ca.pem"
          >>> ServerCertificateFileName="./config/examples/democert.pem"
          >>> ServerKeyFileName="./config/examples/demokey.pem" TrustedCAFileName="./config/examples/ca.pem"/>
          >>> </Server>
          >>>
          >>>
          >>>
          >>>
          >>>
          >>>"Xiang Rao" <[email protected]> wrote:
          >>>>
          >>>>You only need to change Weblogic HTTP configuration. Give the server
          >>>>a big socket
          >>>>Backlog number. Since you test with 100 threads, you can think 1000
          >>>to
          >>>>5000, i.e.,
          >>>>1000 to 5000 requests will be in queue before got served. Aslo, you
          >>>might
          >>>>need
          >>>>to change your OS TCP/IP settings (both test clients and servers),
          >>such
          >>>>as maximum
          >>>>number of sockets and timeout value(so closed sockets will release
          >>socket
          >>>>descriptors
          >>>>immediately).
          >>>>
          >>>>On the other hand, the number of executive threads can be much larger
          >>>>than 15
          >>>>(50-200 is a normal number), depending on the features of your application.
          >>>>You
          >>>>can try your stress test tools to find a reasonable number by analyzing
          >>>>the relationships
          >>>>among (throughtput, response time, number of executive threads, etc).
          >>>>
          >>>>
          >>>>"David Ruana" <[email protected]> wrote:
          >>>>>
          >>>>>My servlet extends HttpServlet so it is multithreaded. Then I have
          >>>written
          >>>>>a java
          >>>>>client which starts 100 concurrent threads that try to contact the
          >>>servlet.
          >>>>>
          >>>>>There are always lots of threads which are refused by the Weblogic
          >>>Server
          >>>>>6.0.
          >>>>>They get a 'Connection refused' exception. Sometimes there are 50
          >>refused
          >>>>>connections,
          >>>>>sometimes there are 0 refused connections (not very often), sometimes
          >>>>>there are
          >>>>>80 refused connections (usually).
          >>>>>
          >>>>>I have checked the 'Servlet' documentation and the 'J2EE Design Considerations
          >>>>>for Weblogic Server' which recommends not to exceede the execute
          >thread
          >>>>>count
          >>>>>number of 15. I have not changed that value, I do not even know if
          >>>it
          >>>>>still exists
          >>>>>in Weblogic 6.0 as the document refers to the 5.0 version.
          >>>>>
          >>>>>Does anybody know how to solve this problem? How can I have the client
          >>>>>requests
          >>>>>waiting rather than being refused? Of course the main goal is to
          >serve
          >>>>>all the
          >>>>>client requests, not to refuse.
          >>>>>
          >>>>>This is the code that the client thread uses to contact the servlet:
          >>>>>
          >>>>>URL url = new URL("http://localhost:7001/examplesWebApp/myServlet");
          >>>>>URLConnection conn = url.openConnection();
          >>>>>conn.setDoInput(true);
          >>>>>conn.setDoOutput(true);
          >>>>>
          >>>>>DataOutputStream os = new DataOutputStream(conn.getOutputStream());
          >>>>>os.writeBytes()
          >>>>>os.writeBytes()
          >>>>>...
          >>>>>
          >>>>>Thanks for your time,
          >>>>>David
          >>>>>
          >>>>
          >>>
          >>
          >