Visual FoxPro Has 3 New SYS Functions Related to Memory (129311)

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SYS(3050) - Set Buffer Memory Size

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.