Re: NT Service Problem

From:
=?Utf-8?B?U3VzYW5uYQ==?= <Susanna@discussions.microsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Mon, 11 Sep 2006 22:06:01 -0700
Message-ID:
<5FA89596-956E-40C1-AF75-E2A5EAE5B593@microsoft.com>
You've got it right , the problem is with not terminating the threads.
I'll try doing a terminatethread on stop.

Also I dont know how to attach a debugger to NT Service, so used the log
files instead.

To debug I just clicked on the NT Service exe in the task manager and
clicked on debug option and it says "Access is denied". Is that how a
debugger is attached?

"Joseph M. Newcomer" wrote:

How do you update the thread count, by the way? If you don't use InterlockedIncrement
there are certain risks.

I'm curious why you keep creating new threads. Also, I don't see where you are closing
the thread handle, which is going to lead to eventual failure.

Again, there isn't really enough information here; you need to attach a debugger and catch
the failure directly.

Log files are an excellent idea, but they won't help if the application crashes before you
log the reason it is going to crash. The typical technique for a log file is
    open file
    append text
    close file
for every update to the log file; you just don't open it and keep writing, because if the
app crashes there is no guarantee that the data is out there successfully. The log file
might help home in on what is really going on and you might spot the problem, but you may
still need to use the debugger.
                joe

On Mon, 11 Sep 2006 11:15:00 GMT, "David" <FlyLikeAnEagle@United.Com> wrote:

Susanna,

Your ServerUpdates method appears to be okay. There could be something
hidden that prevents the shutdown but a debugger is the likely next step.

I'd perform one more test before going to the debugger. Try commenting
out the lines related to beginthread. If your service can now be
shut down properly the problem is in SvrUpdateThreadProc.

When faced with such a misbehavior I usually choose to add to my log
files. In your case I'd add all kinds of logs for the beginning and
ending of threads and all the major resouces that are allocated.

Debuggers are terrific tools when you have a problem you can examine
but rather useless tools when the problem doesn't fail for you. I've
seen more than my share of programs that work on the development
and test systems but fail at some point for the customer. You also
need to be able to determine what happens with your code when it is
released into the wild.

David

On Mon, 11 Sep 2006 09:26:02 UTC, Susanna <Susanna@discussions.microsoft.com> wrote:

void MyService::ServerUpdates()
{

    CDatabase db;
    CString strVal;
    CRecordset rs(&db);
    CString sqlCommand;

    TRY
    {
        //Connect to the Database
        OpenDbConnection(&db);

        if(db.IsOpen())
        {

            sqlCommand = "My SQL Query";
            rs.Open(AFX_DB_USE_DEFAULT_TYPE,sqlCommand);
            DWORD dRowsFetched = rs.GetRowsFetched();
            rs.Close();
            db.Close();

            if(dRowsFetched > 0)
            {

                if(nUpdateThrdCount <= 0) //Global Variable which is greater than
zero if thread below is already started
                {
                    handleUT = (HANDLE) _beginthread(SvrUpdateThreadProc,0,NULL); // create
thread
                    //handleUT global again
                }
                else
                    return;

            }
            else
                return;
        }
        

    }
    CATCH(CDBException, eDB)
    {
        //Write the Error to Log File
    }
    END_CATCH
}

This is the function I am calling in the service every 15 mins to check for
a condition
If the condition is satisfied a new thread is started.

I am also calling this function in ServiceMain

The Service starts & stops successfully if I dont call this function.
If this function is called then there is a problem in stop of service.
The service is eventually stopped , but it does not return Success.

{There are other functions also that I am calling from service main & they
also deal with threads, but I dont have any problems with those.
Its just this function that is causing problems}

Has this something to do with the time out value.
How can I extend the timeout period for stopping the service.If yes, how?

Thanks again for your help!

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

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