Does sleep time count for execution time limit?

Question

I have two questions concerning the sleep() function in PHP:

1. Does the sleep time affect the maximum execution time limit of my PHP scripts? Sometimes, PHP shows the message "maximum execution time of 30 seconds exceeded". Will this message appear if I use sleep(31)?

2. Are there any risks when using the sleep()function? Does it cost a lot of CPU performance?

Answer 1

You should try it, just have a script that sleeps for more than your maximum execution time.

<?php   sleep(ini_get('max_execution_time') + 10); ?> 

Spoiler: Under Linux, sleeping time is ignored, but under Windows, it counts as execution time.

Answer 2

It only affects script time not system calls like sleep(). There is apparently a bug where on Windows sleep() is included. Max execution time is about real-time, not CPU time or anything like that. You can change it however:

• max_execution_time directive in your php.ini. This is a global setting;
• Using ini_set() with the above directive. This will change it only for the currently executing script only for that execution;
• set_time_limit(): also a local change.

As for the difference between the last two, I believe max_execution_time is a fixed quantity. Running:

ini_set('max_execution_time', 60); 

will limit to the script to 60 seconds. If after 20 seconds you call:

set_time_limit(60); 

the script will now be limited to 20 + 60 = 80 seconds.