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 From: Paul Gibson
  Where is Paul Gibson?
 United Kingdom
 Paul Gibson
 To: Scott Brush
  Where is Scott Brush?
 Pennsylvania - United States
 Scott Brush
Subject: RE: Intermittent application freezes
Thread ID: 395726 Message ID: 395729 # Views: 50 # Ratings: 3
Version: Visual FoxPro 9 Category: Network and Computer Management
Date: Friday, January 17, 2014 6:07:26 PM         

> Scott Brush
> www.scottmbrush.com
> I'm maintaining a VFP application over a network. My users have an intermittent issue where suddenly, their screens will freeze for a minute or two and then resume working. No errors are reported by the system when this happens. Does anyone know what might be causing this?

When the user reports that the screen freezes is it the "whole screen" (i.e. the whole Windows desktop becomes unresponsive) or just your application. It's an important detail because if Windows is still responsive but your application is not then that would suggest something in your application is hanging. If it's the whole desktop then that would suggest something in the operating system/configuration of the machine is hanging the whole machine in which case your application could possibly be an innocent party.

If it does appear to be your application you could investigate it by using Coverage Logging, where you could run your application with a SET COVERAGE command (or COVERAGE= in your config.fpw file) logging all lines of code into a log file which you later examine to see if there are any lines of code that are taking a long time.

When I examine coverage logs I import the data into a table and browse for any lines of code where the duration > 0.5 (seconds). Realistically every line of code should be taking a short amount of time so the only hits should be where a main program has called a function and the total time the function took (all the lines of code executed within the function and any child functions) exceeded the amount of time in my query or BROWSE FOR command. Debugging via coverage logging is not always the easiest to begin with but once you master the technique it is incredibly powerful for finding issues.

Even if you are not specifically debugging it does allows you to find problem areas in your code. Hopefully the issue is not at your end but something on your users machine(s) which is hanging the machine for a short while.


Intermittent application freezes Posted by Scott Brush @ 1/17/2014 3:49:32 PM
RE: Intermittent application freezes Posted by Stefan Wuebbe @ 1/17/2014 5:17:23 PM
RE: Intermittent application freezes Posted by Paul Gibson @ 1/17/2014 6:07:26 PM