July 24, 2008 07:47pm pdt

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	[x] Attachment Details

2.5 second "pause" between when code exits and command line comes back (ThreadExit)

Zones: C Programming Language, Windows Programming

Tags: C

I have a Win32 command line application that uses ODBC calls to access any database. Everything seems to be working great, except for a minor performance issue that we are now battling. At the end of the code, as the application is termination, we are seeing a "pause" that can run as long as 2.5 seconds (or more).

This is not in my code, but rather is AFTER my code exits. The end of the application looks like this:
      if(DisplayTimes)
            PrintTime("Tearing Down SQL Environment");
      TearDownSQLEnvironment();
      if(DisplayTimes)
            PrintTime("Complete!");
      exit(ReturnStatus);
}

When run, I get a list of timestamps including the following:

18:29:43.650: Finished Data Read
18:29:43.650: Free Statement Handle
18:29:43.650: Disconnect from Database
18:29:43.728: Tearing Down SQL Environment
18:29:43.728: Complete!

As you can see, the call to disconnect from the database takes some time, but tearing down the environment takes almost no time at all. The problem, though, is that the program is exiting, but control is not returned to the command line for some time thereafter. The code snippet shows a Process Monitor trace that shows that the Thread Exit call is occurring at 18:29:43.719 (actually a bit BEFORE the program actually finishes, but this could be a timer issue). In any event, nothing happens for the next 2.5 seconds and we sit there waiting for the command prompt to come back. Even checking through the intervening calls with ProcMon, I don't see anything other than the typical "idle chatter" of AV and other agents. (No, AV is not the issue, as I can duplicate the problem on other systems with no AV code.)

The application I am using is called SQLExec, and is also available for download from www.goldstarsoftware.com/tools.asp. You can test it yourself to any ODBC database by issuing a command like this:
SQLEXEC <DSNName> "SELECT TOP 1 * FROM TableName" /DT

The app is fast, but the delay FOLLOWING the app is positively maddening! Help!

I've surmised that this is unloading of DLL's related to ODBC and the database, but I have not found a way to confirm this as of yet.

         
             17145	18:29:43.7198046	sqlexec.exe	4640	Thread Exit		SUCCESS	User Time: 0.0000000, Kernel Time: 0.0000000
18:29:46.2529335	sqlexec.exe	4640	RegOpenKey	HKLM\Software\Microsoft\Windows NT\CurrentVersion\GRE_Initialize	SUCCESS	Desired Access: Read
18:29:46.2529836	sqlexec.exe	4640	RegQueryValue	HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\GRE_Initialize\DisableMetaFiles	NAME NOT FOUND	Length: 20
18:29:46.2530469	sqlexec.exe	4640	RegCloseKey	HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\GRE_Initialize	SUCCESS	
18:29:46.2531342	sqlexec.exe	4640	Thread Exit		SUCCESS	User Time: 0.0312500, Kernel Time: 0.2031250
18:29:46.2542871	sqlexec.exe	4640	Process Exit		SUCCESS	Exit Status: 0, User Time: 0.0468750, Kernel Time: 0.1562500
18:29:46.2545963	sqlexec.exe	4640	CloseFile	C:\Develop\Win32\SQLExec\Release	SUCCESS	
18:29:46.2548343	sqlexec.exe	4640	CloseFile	C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.2982_x-ww_ac3f9c03	SUCCESS

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Question Stats

Zone: Programming

Question Asked By: BillBach

Solution Provided By: Infinity08

Participating Experts: 5

Solution Grade: A

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