PRB: IDE May Skip Some TRACE Statements Sent in Quick Succession

ID: Q218007

The information in this article applies to:

Microsoft Visual C++, 32-bit Editions, versions 5.0sp3, 6.0
on the following platforms: NT, Win95, Win98
Windows 2000

SYMPTOMS

While debugging a Visual C++ application, if TRACE statements are sent to the output window consecutively in quick succession, the IDE tends to skip some statements.

CAUSE

When TRACE statements are sent in quick succession, the IDE buffers the strings. It tries to keep the screen output current, so in the event of too many calls to OutputDebugString to accomplish that, some lines are skipped.

RESOLUTION

Currently, there is no workaround to this problem. _RPT() and the SDK sample DBMON, which is a similar utility, could be used if all the consecutive TRACE statements need to be captured in the output window, while debugging.

STATUS

This behavior is by design.

MORE INFORMATION

This scenario can be easily reproduced using a combination of TRACE statements as shown below:


int i, j, k;
TRACE(_T("Start TRACE Check\n"));
for (i=0; i<20; i++)
{
   TRACE(_T("Outer Loop %d\n"), i);
    for (j=0; j<20; j++)
    {
      TRACE(_T("\tInner Loop %d\n"), j);
      for (k=0; k<20; k++)
      {
        TRACE(_T("\t\tCore Loop %d\n"), k);
      }
   }
}

TRACE(_T("End TRACE Check\n"));

When trying to debug an application with the above code, the output window will resemble the following code snippet:


    Inner Loop 3
        Core Loop 1
        Core Loop 2
        Core Loop 3
        Core Loop 4
        Core Loop 5
        Core Loop 6
        Core Loop 18
        Core Loop 19
        Core Loop 3
        Core Loop 4
        Core Loop 5
        Core Loop 6
    Inner Loop 14
        Core Loop 1

The output window does not consistently show the same pattern when skipping TRACE statements; rather, it shows different patterns depending on machine speed and number of iterations.

REFERENCES

Additional query words:

Keywords : kbCRT kbDebug kbWinOS2000 kbVC500 kbVC600 kbDSupport
Version : winnt:5.0sp3,6.0; :
Platform : winnt
Issue type : kbprb