Looping Question

[codewalker]

Hi,

Is there a difference in using a WHILE...WEND loop vs a DO...UNTIL loop performance wise? I have a DO...UNTIL infinite loop with a condition in it to exit the loop and a SLEEP command to hopefully help but some users experience performance issues. Any tips on using infinite loops without degrading performance?

[water]

Yes, there is.

While: The expression is tested before the loop is executed.

Do Until: The expression is tested after the loop is executed.

So the Do Until Loop runs at least once.

[codewalker]

Yes, there is.

While: The expression is tested before the loop is executed.

Do Until: The expression is tested after the loop is executed.

So the Do Until Loop runs at least once.

Thanks for the reply. That i know but is there a difference in their performance? Noticed that most of the infinite loop examples in the forums use WHILE...WEND, is there an advantage in using it againts DO...UNTIL? I used DO...UNTIL in one of my scripts and it's slowing down some users workstations. Any ideas?

[water]

I don't think there is a difference in performance:

$iIndex = 0
$iLoops = 10000000
$iTimer = TimerInit()
While $iIndex < $iLoops
    $iIndex = $iIndex + 1
Wend
ConsoleWrite(TimerDiff($iTimer) & @CRLF)
$iIndex = 0
$iTimer = TimerInit()
Do
    $iIndex = $iIndex + 1
Until $iIndex > $iLoops
ConsoleWrite(TimerDiff($iTimer) & @CRLF)

returns:

9259.90794696208

9207.17102991027

here

[codewalker]

Thanks! Any ideas though on how or why an infinite loop would cause a program executed via a RUN command before the loop to freeze? Does having a SLEEP command in the loop have any effect on responsiveness?

Edited August 22, 2011 by codewalker

[water]

If you can post the code (at least the part with the loop) we can have a look at it.

[codewalker]

If you can post the code (at least the part with the loop) we can have a look at it.

Its something like this...

Run(...)

Do

Sleep(1000)

...

If Not ProcessExists(...) Then Exit 0

...

Until ...

I was using WINEXISTS before but learned that there were a lot of factors that would NOT trigger it so i went and used loops instead. Using the script indicated above causes the program that was launched by the RUN command to lockup, at least with some users.

Edited August 22, 2011 by codewalker

[water]

You have two conditions to exit the loop. One is "If Not processExists ..." the other is "Until ...". is this what you intend to do?

If you just want to wait until the process has stopped then I would suggest to use something like this:

While 1
   Sleep(1000)
   ...
   If Not ProcessExists(...) Then Exit 0
Wend

Edited August 22, 2011 by water

[Syed23]

Hi Codewalker,

i tried Water example i got the below values:

For While loop - 12762.1928057139

For Di Loop - 12770.5848202678

There is 8 ms difference between both definite loop. If you are saying you have indefinite loop then i could suggest to go for While ...wend to more quick results....As for as i don;t know the reason but i will try to find out:).... Water please correct me if i am wrong... There may be a chances of machine capacity for response.. I am having 1GB Ram so i got the response time of above if water response time is less than mine so his machine may faster then mine.... so also try to look in to that way to trouble shoot it....

[water]

Hi Syed,

I don't think the speed difference is a matter of RAM. It's a matter of CPU speed and X86 vs. X64.

Run as X86 it takes about 11300 ms, run as X64 it takes about 9200 ms.

[codewalker]

Thanks for the replies guys.

This maybe unrelated but just read somewhere that there are instances that SLEEP locks up or hangs the whole process...at least in VB. Could that be what is causing the lockup in my script? Their fix was to have a DOEVENTS but is there a similar command in AutoIt?

[water]

There are situations where a Sleep in your code is a bad idea. A function registered by AdlibRegister comes to my mind. Or a long Sleep in a tight loop where AutoIt itself handles the "sleep" and maybe some more.