Short Sleeps

Problem

You need to sleep for less than a second.

Solution

Use the select() function, if your system supports it: 

select(undef, undef, undef, $time_to_sleep);

Some systems don't support a four-argument select. The Time::HiRes module provides a sleep function that takes a floating point number of seconds: 

use Time::HiRes qw(sleep); sleep($time_to_sleep);

Discussion

Here's an example of select. It's a simpler version of the program in . Think of it as your very own 300-baud terminal. 

while (<>) {
 select(undef, undef, undef, 0.25); print;
}

Using Time::HiRes, we'd write it as: 

use Time::HiRes qw(sleep); while (<>) {
 sleep(0.25); print;
}

See Also

The documentation for the CPAN modules Time::HiRes and BenchMark; the sleep and select functions in perlfunc (1) and of Perl Programming; we use the select function for short sleeps in the slowcat program in

High-Resolution Timers Perl tutorial Program: hopdelta
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