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Thread: jdbc connections

  1. #1
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    Question jdbc connections

    I had existing function (f1) that opens and does select sql and returns results and closes connection.

    Now I need to call the f1 many time. so in a loop

    loop begins
    f1
    loop ends.

    As long as the f1 opens and closes the jdbc connection I should not have any problem whatever the number of times it loops.

    But I do see problem max connections sql exception

    java.sql.SQLException: Network error IOException: No buffer space available (maximum connections reached?): connect
    at net.sourceforge.jtds.jdbc.ConnectionJDBC2.<init>(C onnectionJDBC2.java:385)
    at net.sourceforge.jtds.jdbc.ConnectionJDBC3.<init>(C onnectionJDBC3.java:50)
    at net.sourceforge.jtds.jdbc.Driver.connect(Driver.ja va:182)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.cleverdevices.bustime.util.DatabaseUtil.openDa tabaseConnection(DatabaseUtil.java:68)
    at com.cleverdevices.bustime.scheduleevaluator.Schedu leEvaluator.getHistoricalScheduleAdherenceResults( ScheduleEvaluator.java:877)
    at com.cleverdevices.bustime.scheduleevaluator.Schedu leEvaluatorIFImpl.getHistoricalScheduleAdherenceRe sults(ScheduleEvaluatorIFImpl.java:450)
    at sun.reflect.GeneratedMethodAccessor3.invoke(Unknow n Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
    at sun.rmi.transport.Transport$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at sun.rmi.transport.Transport.serviceCall(Unknown Source)
    at sun.rmi.transport.tcp.TCPTransport.handleMessages( Unknown Source)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandl er.run0(Unknown Source)
    at sun.rmi.transport.tcp.TCPTransport$ConnectionHandl er.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run Task(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run (Unknown Source)
    at java.lang.Thread.run(Unknown Source)
    Caused by: java.net.SocketException: No buffer space available (maximum connections reached?): connect
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(Unknown Source)
    at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at sun.reflect.GeneratedMethodAccessor4.invoke(Unknow n Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Un known Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at net.sourceforge.jtds.jdbc.SharedSocket.createSocke tForJDBC3(SharedSocket.java:304)
    at net.sourceforge.jtds.jdbc.SharedSocket.<init>(Shar edSocket.java:255)
    at net.sourceforge.jtds.jdbc.ConnectionJDBC2.<init>(C onnectionJDBC2.java:310)
    ... 20 more


    obviously if I connection before loop and close after loop it is ok. But my theory as long as we close everytime it should work ..

    what is missing. "netstat" lists the db connections ports..

    ofcourse when I stop the tomcat server..it clears.


  2. #2
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    Default Re: jdbc connections

    Provide an SSCCE (or as close as you can get) detailing what is causing the exception - we cannot comment on code that we do not know about

  3. #3
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    Default Re: jdbc connections

    my question in not regarding my code.

    My questions is if we loop open/close connection lets say 20k to 30k times, will that be a problem? I thought as long as we open and close, it should not be a problem. or is there a limitation?

  4. #4
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    Default Re: jdbc connections

    Quote Originally Posted by rlk View Post
    my question in not regarding my code.

    My questions is if we loop open/close connection lets say 20k to 30k times, will that be a problem? I thought as long as we open and close, it should not be a problem. or is there a limitation?
    Honestly I never tried it - theoretically it should work, but in my opinion is very bad practice.

  5. #5
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    Default Re: jdbc connections

    thanks. In my try, it did not work and i got max connections reached exception. I moved the open/close outside the loop. I also thought theoratically it should work. but looks like the loop goes faster that the open/close.

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