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  1. #1
    Join Date
    Nov 2004
    Posts
    3

    Unanswered: intermittent locks

    We are experiencing problems intermittently.

    Users report problems of various types including timeout messages. We investigate and find a user has acquired a lock which is blocking other users.

    We contact the user and they have usually completed their activity and are not always aware of any problem despite them owning a lock.

    When the user logs out of the application the lock clears and the system returns to normal.

    Indexes have been rebuilt, auto update statistics is on.

    Does anyone have any suggestions?

  2. #2
    Join Date
    Feb 2004
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    Provided Answers: 54
    The first thing I'd do is start watching for locks to determine how often they occur, and ask the users if they know of any activity that causes the problems associated with locking/blocking (that may give you clues about what you need to watch).

    Once you understand what you are looking for, run a trace using SQL Profiler at the same time as a Performance Monitor trace watching for locking/blocking. The PerfMon trace will show you when the problem occurs, the Profiler trace will show you what caused the problem.

    When you understand the cause of the problem, you can then look at changing the application to avoid the problem.

    -PatP

  3. #3
    Join Date
    Nov 2004
    Posts
    3
    We are trying to gather more information from the users to track this down.

    Anecdotally users believe that they have finished their activity and are simply still logged on or are running searches.

    We haven't needed to kill a session, the user simply logs off.

    It's almost as though the lock has been taken but not released when the activity has finished.

    Does this sound likely/possible? If so any ideas what could be causing it?

  4. #4
    Join Date
    Feb 2004
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    15,579
    Provided Answers: 54
    Quote Originally Posted by grimwyre
    Does this sound likely/possible? If so any ideas what could be causing it?
    Yes, it sounds rather likely.

    I'd suspect that the problem is something that the code is doing "behind the curtains" that the user is completely unaware of, but is still causing havok. Until you can compare the two traces (or provide LOTS of additional insight into your application and server configuration), we can only guess.

    -PatP

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