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JDBC Driver Mystery Hangs - IBM DB2

Hi all, I've been testing some code in Junits test in Netbeans against a DB2 8.1.2 DB Fixpak 3 server (Linux). Because each test is descrete the first part of it loads up the classes needed to run the test. I.e. Each test does exactly the same sequence of class and data loading. I've encountered (a number of times) where the JDBC driver will hang on a SQL (often a simple select) that it has successfully executed in a previous test. I go into full on debug mode - activating System.out's etc to see whats going on. In every case ...

  1. #1

    Default JDBC Driver Mystery Hangs

    Hi all,
    I've been testing some code in Junits test in Netbeans against a DB2 8.1.2
    DB Fixpak 3 server (Linux). Because each test is descrete the first part of
    it loads up the classes needed to run the test. I.e. Each test does exactly
    the same sequence of class and data loading.

    I've encountered (a number of times) where the JDBC driver will hang on a
    SQL (often a simple select) that it has successfully executed in a previous
    test. I go into full on debug mode - activating System.out's etc to see
    whats going on. In every case it is the Statement.execute() method running
    a sql that has worked fine before. I try changing the way the code works
    and am not able to get rid of the hang.

    Eventually I tried re-arranging the order of the tests. To my surprise the
    hang started moving around. Always in the same test and statement until I
    re-arranged them, then it would be in a different test. Eventually I worked
    out that the hang was moving in relation to an error that was appearing in
    one of the other tests. It also always appeared in the same SQL statement,
    although in a different test.

    I killed this other error and the hang disappeared. I don't have the
    facilities to debug this, but it appears as if the driver throws an error,
    keeps working and then at some later stage, hangs. Possibly on a similar
    type of statement or some statement that does something to it internally.

    Thats about as definite as I can get at the moment. I'm concerned that it
    can lead to all sorts of strange program crashes and hangs.

    has anyone else encountered this ???

    cio
    Derek.
    Derek Clarkson Guest

  2. #2

    Default Re: JDBC Driver Mystery Hangs


    Derek Clarkson wrote:
    > Hi all,
    > I've been testing some code in Junits test in Netbeans against a DB2 8.1.2
    > DB Fixpak 3 server (Linux). Because each test is descrete the first part of
    > it loads up the classes needed to run the test. I.e. Each test does exactly
    > the same sequence of class and data loading.
    >
    > I've encountered (a number of times) where the JDBC driver will hang on a
    > SQL (often a simple select) that it has successfully executed in a previous
    > test. I go into full on debug mode - activating System.out's etc to see
    > whats going on. In every case it is the Statement.execute() method running
    > a sql that has worked fine before. I try changing the way the code works
    > and am not able to get rid of the hang.
    >
    > Eventually I tried re-arranging the order of the tests. To my surprise the
    > hang started moving around. Always in the same test and statement until I
    > re-arranged them, then it would be in a different test. Eventually I worked
    > out that the hang was moving in relation to an error that was appearing in
    > one of the other tests. It also always appeared in the same SQL statement,
    > although in a different test.
    >
    > I killed this other error and the hang disappeared. I don't have the
    > facilities to debug this, but it appears as if the driver throws an error,
    > keeps working and then at some later stage, hangs. Possibly on a similar
    > type of statement or some statement that does something to it internally.
    >
    > Thats about as definite as I can get at the moment. I'm concerned that it
    > can lead to all sorts of strange program crashes and hangs.
    >
    > has anyone else encountered this ???
    >
    > cio
    > Derek.
    Have you checked the lock snapshot?

    Fan Ruo Xin Guest

  3. #3

    Default Re: JDBC Driver Mystery Hangs

    Fan Ruo Xin wrote:
    > Have you checked the lock snapshot?
    Nope, wasn't aware of it, thanks. Next time I get this I'll have a look and
    see whats going on. For the moment everythign is working again.

    cio
    Derek.
    Derek Clarkson Guest

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