What is a practical use for PHP's sleep()?

Question

I just had a look at the docs on sleep().

Where would you use this function?

Is it there to give the CPU a break in an expensive function?

Any common

Answer 1

This is a bit of an odd case...file transfer throttling.

In a file transfer service we ran a long time ago, the files were served from 10Mbps uplink servers. To prevent the network from bogging down, the download script tracked how many users were downloading at once, and then calculated how many bytes it could send per second per user. It would send part of this amount, then sleep a moment (1/4 second, I think) then send more...etc.

In this way, the servers ran continuously at about 9.5Mbps, without having uplink saturation issues...and always dynamically adjusting speeds of the downloads.

I wouldn't do it this way, or in PHP, now...but it worked great at the time.