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Re^4: weird case of memory corruption? -- Tk ProgressBar bugged?

by Discipulus (Abbot)
on May 12, 2021 at 11:28 UTC ( #11132466=note: print w/replies, xml ) Need Help??


in reply to Re^3: weird case of memory corruption? -- Tk ProgressBar bugged?
in thread weird case of memory corruption?

Hello Marshall,

this is exatcly the point: my code show the bug that happens only sometimes. Try to execute the code many times:

>perl tkprogressbar2.pl Use of uninitialized value in numeric ge (>=) at tkprogressbar2.pl lin +e 31. WARNING: $pid{ex1}{val} NOT FOUND!! ("ex1", { as => "temp", val => undef }) >perl tkprogressbar2.pl >perl tkprogressbar2.pl >perl tkprogressbar2.pl >perl tkprogressbar2.pl Use of uninitialized value in numeric ge (>=) at tkprogressbar2.pl lin +e 31. WARNING: $pid{ex1}{val} NOT FOUND!! ("ex1", { as => "temp", val => undef })

L*

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Re^5: weird case of memory corruption? -- Tk ProgressBar bugged?
by Marshall (Canon) on May 12, 2021 at 11:44 UTC
    OK. Your point is accepted and verified by me on Perl v5.24.

    I actually saw this in my testing, but I couldn't believe my own eyes!
    The exact same source code can produce different results when run more than once.

    I am flabbergasted! This is true, but I don't know why or how?

    More Info:
    Updating a Windows GUI is an extremely expensive operation.
    If you have a loop that will do say 10,000 operations, and you want to show progress via a percent or a progress bar, calculate whether or not the progress bar will move before you update the GUI's value - do this at most 100 times (each one percent for a 100% bar) and probably less than that! The difference in performance between calling the GUI 10,000 times vs 100 times is astonishing!

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