BUG: Repeatedly Calling Genxtab Can Cause Memory Leak

ID: Q194886

The information in this article applies to:

Microsoft Visual FoxPro for Windows, versions 3.0b, 5.0, 5.0a, 6.0

SYMPTOMS

Repeatedly calling Genxtab.prg within a program causes Visual FoxPro 3.0x and 5.0x to lose one memory handle in each iteration of the loop after the first pass. This problem does not occur in Visual FoxPro 6.0.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

Steps to Reproduce Behavior

Create a program that contains the following code:


      CLEAR
      SET SAFETY OFF
      FOR i = 1 TO 200
         ? "Run Number: " + STR(i), SYS(1016), SYS(1011)
         SELECT to_country,ship_via,order_net FROM orders ;
         ORDER BY to_country, ship_via ;
         GROUP BY to_country, ship_via INTO TABLE bob
         DO (_GENXTAB) WITH ('bob1'), , , , , , ,.T.
      NEXT
      SET SAFETY ON

Run the program and notice the number of memory handles, the last number on each line, increase by one with each iteration after the first pass. Eventually, the system may report a memory error such as:

Windows 95

VFP caused an invalid page fault in module KERNEL32.DLL at <memory address>.

-or-
Windows NT 4.0

vfp.exe
Exception: access violation(0x0000005), Address: <memory address>

However, to experience the system error message, you may need to increase the number of iterations in the FOR...NEXT loop.

Additional query words:

Keywords : kbMiscTools kbVFp600 kbXBase
Version : WINDOWS:3.0b,5.0,5.0a,6.0
Platform : WINDOWS
Issue type : kbbug