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Q191953: HOWTO: Use Coverage Profiler to Optimize App Performance

Article: Q191953
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): 
Last Modified: 11-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
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SUMMARY
=======

A coverage application writes information about which lines of code were run in
a file. A profiler application provides information about which lines actually
run, how many times a line is run, duration, and more. Coverage and profiler
enable a developer to identify problem areas in an application, especially
skipped code and performance bottlenecks. Using this tool you are able to
identify parts of your code that have not been executed during your testing.

MORE INFORMATION
================

There are many different ways to test your code. One of the ways is to make sure
that every line of code has been run at least once or more during your normal
testing pass.

To start the Coverage Profiler, you need to create a Log file by issuing the
following command:

  SET COVERAGE TO C:\MYLOGFILE.LOG 

(may have any random file name)

By issuing this command you create the LOG file and turn on the Coverage
Profiler. Since the Coverage Profiler has been started, you can run your program
or application and everything is recorded into your Log file.

NOTE: These log files can grow quickly to be very large in size so you may wish
to test sub sets of your code at any one time to conserve hard disk space.

Once you have completed running your application or program, you can run the
Coverage Profiler from the Tools menu in Visual FoxPro 6.0.

Once the Coverage Profiler is completed analyzing the Log file it will put the
Coverage Profiler dialog into one of two modes; the Coverage Mode or the Profile
Mode. The mode can be changed easily by selection of a button on the Coverage
Profiler toolbar.

The Coverage Mode allows you to view each line of code and determine whether or
not that line of code was run at any time during your testing.

The Profile Mode shows you each line of code and how many times it was hit along
with how long it took to run the first time and on average.

Before you start looking at the code log file line by line, you might like to get
a quick overview of how well your code executes. Click the toolbar button
labeled Statistics. This gives you a quick overview of how many lines of code
were executed verses how many were not. If you did not get 100% Covered
Linecount, then you probably did not execute all possible scenarios of your code
in your test run.

The Options toolbar button presents you with a dialog box that allows you to
alter and store certain preferences for use by the Coverage Profiler. Click the
Options toolbar button to open up the Options dialog box. In addition to your
choice of Display Font, Start Mode, and Environment frame, you can also change
the Coverage mark from its defaults to something that you prefer, like $$$ for
the Executed lines or ### for the Not Executed lines. Select the Set as Default
check box if you wish to preserve your changes. When you close the Options
dialog box you will be asked to preserve current marked records or Empty and
re-mark these records. You should then choose No, to Empty and re-mark the
records. You will see these coverage marks in the Coverage Mode to the left of
each line of code. You can now go through your code line by line and identify
each line of code that did not get executed by your test run. This helps you to
identify parts of your code that still need to be executed the next time you run
through your test.

To identify bottlenecks or lines of code that are potential performance problems,
use the Profile Mode. You can scan down through your code looking for lines that
have large numbers of hits or a long average execute time. To improve
performance, check to see if you can find a faster way of performing the same
task that is done by that line of code.

There are many other third party tools that can help you test your Visual FoxPro
code, but Microsoft has provided the Coverage Profiler as a way of getting
started down the testing path.

REFERENCES
==========

Visual FoxPro 6.0 Help, search on: "Coverage Profiler Application"

Additional query words: PGFest600 kbXBase kbMiscTools kbVFp600

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Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0
Issue type        : kbhowto

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