Q129311: Visual FoxPro Has 3 New SYS Functions Related to Memory

Article: Q129311
Product(s): Microsoft FoxPro
Version(s): WINDOWS: 3.0,5.0,6.0
Operating System(s): 
Keyword(s): 
Last Modified: 14-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 5.0, 5.0a, 6.0 
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SUMMARY
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There are three new SYS functions in Visual FoxPro related to memory.

The new functions are:

- SYS(3050), which sets buffer memory size.

- SYS(3051), which sets lock retry interval.

- SYS(3052), which overrides SET REPROCESS locking.

MORE INFORMATION
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SYS(3050) - Set Buffer Memory Size
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SYS(3050, nType, nBuffMemSize)

- nType specifies foreground (1) or background (2)

- nBuffMemSize specifies a suggested, maximum amount of buffer memory you want
  Visual FoxPro to commit in foreground or background mode.

The foreground memory buffer is the amount of memory available to Visual FoxPro
when it is the currently active application. The background memory buffer is the
amount of memory for use when Visual FoxPro is in the background with another
application running in the foreground. Visual FoxPro never sets the target to
more than the amount of physical RAM on the computer and never sets it to less
than 256K bytes. Passing a zero for nBuffMemSize will cause Visual FoxPro to
reset to its startup value, which is 262144 for both background and foreground.

This function should be used in place of the MEMLIMIT command that was placed in
the Config.fpw file in previous versions of FoxPro. The MEMLIMIT command is
ignored in Visual FoxPro.

To set the foreground or background buffer memory size to 6 and 4 million
respectively, create a program and call it from the Config.fpw file. For
example, add the following line to call Myprogram.prg from the Config.fpw file.
Remember, only one Command= line is allowed in the Config.fpw file.

     COMMAND = DO Myprogram.prg

Create a program file called Myprogram.prg in the root folder of Visual FoxPro
and type the following code:

     =SYS(3050,1,6000000)
     =SYS(3050,2,4000000)

For these changes to take effect, restart Visual FoxPro. To check the validity of
these settings, type the following in the Command window:

     ? SYS(3050,1)
     ? SYS(3050,2)

SYS(3051) - Set Lock Retry Interval
-----------------------------------

SYS(3051, nWaitMilliseconds)

- nWaitMilliseconds specifies the suggested interval of time for Visual FoxPro
  to wait between retries while attempting to lock a record, file, memo, or
  index. The valid range is from 100 to 1000 milliseconds. Passing a zero for
  nWaitMilliseconds will cause Visual FoxPro to reset to its startup value
  which is 333.

SYS(3052) - Honor REPROCESS for Index or Memo Lock Attempts
-----------------------------------------------------------

SYS(3052, nFileType, lHonorReprocess)

- nFileType specifies index (1) or memo (2).

- lHonorReprocess, when equal to .T., specifies that Visual FoxPro should honor
  the SET REPROCESS setting when Visual FoxPro attempts to lock files. When
  lHonorReprocess is off (.F.), the locking behavior is to wait indefinitely
  for locks on the specified files. Honoring SET REPROCESS is recommended if
  your program is using transactions because reduces the risk of deadlocks.
  Turning it on for indexes may adversely impact concurrency control because
  index locks may be held for a longer period of time.

Using SYS(1001) and SYS(1016)
-----------------------------

SYS(1001) returns the virtual memory pool size. SYS(1016) returns the amount of
memory used by defined objects. However, in order to get accurate memory
statistics, you should use Window API functions.

Additional query words: VFoxWin

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Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP500 kbVFP600 kbVFP500a
Version           : WINDOWS: 3.0,5.0,6.0

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