PHP fgets loads CPU to 100%

All we need is an easy explanation of the problem, so here it is.

I’ve made read key press function in PHP. The code sets non-block stream mode for STDIN and in while waits when STDIN will receive any data. It works, but I noticed that function loads CPU to 100%. How much is bad this code for CPU and is there any another way to check is STDIN contains any data?

    $stdin = fopen("php://stdin", "r");
    stream_set_blocking($stdin, false);
    system("stty cbreak -echo");

    while (true)
    {
        if ($keypress = strtoupper(fgets($stdin)))
        {
            break;
        }
    }
    stream_set_blocking($stdin, true);

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

My problem was resolved after I added time_nanosleep for 5 milliseconds on each loop iteration:

$stdin = fopen("php://stdin", "r");
stream_set_blocking($stdin, false);
system("stty cbreak -echo");
$t = 1000000;
while (!($keypress = strtoupper(fgets($stdin))))
{
    time_nanosleep(0, 5 * $t);
}
stream_set_blocking($stdin, true);

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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