How to resolve the issue when the sleep function in PHP is not executing?

If the sleep() function is not executed in PHP, it may be due to several reasons.

1. The sleep function is disabled in the PHP configuration file. You can check the php.ini file to make sure that the disable_functions setting does not include sleep.
2. The security policy in the PHP runtime environment has disabled the sleep function. You can use the phpinfo() function to check the current security policy settings in the PHP environment and compare them with functions related to sleep.
3. There was a code error in the PHP program that caused the sleep function to not execute. You can check for syntax errors, logical errors, or any other issues that may be preventing the program flow from reaching the sleep function.
4. Other PHP extensions related to the sleep function may not have been properly loaded or installed. You can use the extension_loaded function to check if the relevant extensions have been loaded, or check the PHP error log for possible error messages.

If the above methods are still unable to solve the problem, it is advisable to try using other ways to implement delays in PHP programs, such as using the usleep function or timers.