Re^2: missing second of time

Don't sleep FOR one second, sleep until the NEXT second.

Thanks for the lightbulb. I see no error since doing it that way. I wonder if the perldoc for sleep should add something like:

Explain why this is a subtle trap:

while () {
  print something();
  sleep 1 # WRONG!
}

use Time::HiRes qw/sleep time/;
while () {
  print something();
  sleep do { (int time + 1) - time } # RIGHT!
}

Maybe it's already a FAQ? I don't know. Thank you!

Comment on Re^2: missing second of time

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Re^3: missing second of time by LanX (Saint) on Jan 25, 2020 at 23:11 UTC
You are missing the conceptual loophole here. > `print something();` So what if `something()` takes longer than a second? Your sleep would just skip the missed steps till the following interval. The clean approach would be to include an exception handling. Apart from this could the OS be too busy to return in time, that's why sleep only guaranties minimal time. See Re: missing second of time > I wonder if the perldoc for sleep should add ... All these conditions might not be true in your case, but how do you want to include the general case in the docs??? I think this use cases are best covered in a dedicated module. Update Might be interesting to compare how setInterval() in JS is handling those cases. Update From what I read after searching JS setInterval long running function it seems that delayed calls are queued to be executed later, and this without raising an exception. ... Ugly. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply] [d/l] [select]

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Re^3: missing second of time
by LanX (Saint) on Jan 25, 2020 at 23:11 UTC

You are missing the conceptual loophole here.

> print something();

So what if something() takes longer than a second?

Your sleep would just skip the missed steps till the following interval.

The clean approach would be to include an exception handling.

Apart from this could the OS be too busy to return in time, that's why sleep only guaranties minimal time.

See Re: missing second of time

> I wonder if the perldoc for sleep should add ...

All these conditions might not be true in your case, but how do you want to include the general case in the docs???

I think this use cases are best covered in a dedicated module.

Update

Might be interesting to compare how setInterval() in JS is handling those cases.

Update

From what I read after searching JS setInterval long running function it seems that delayed calls are queued to be executed later, and this without raising an exception. ... Ugly.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery
FootballPerl is like chess, only without the dice}

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