(PHP 5, PHP 7, PHP 8)

proc_niceChange the priority of the current process


proc_nice(int $priority): bool

proc_nice() changes the priority of the current process by the amount specified in priority. A positive priority will lower the priority of the current process, whereas a negative priority will raise the priority.

proc_nice() is not related to proc_open() and its associated functions in any way.



The new priority value, the value of this may differ on platforms.

On Unix, a low value, such as -20 means high priority wheras a positive value have a lower priority.

For Windows the priority parameter have the following meanings:

Priority class Possible values
High priority priority < -9
Above normal priority priority < -4
Normal priority priority < 5 & priority > -5
Below normal priority priority > 5
Idle priority priority > 9

Return Values

Returns true on success or false on failure. If an error occurs, like the user lacks permission to change the priority, an error of level E_WARNING is also generated.


Version Description
7.2.0 This function is now available on Windows.


Example #1 Using proc_nice() to set the process priority to high

// Highest priority


Note: Availability

proc_nice() will only exist if your system has 'nice' capabilities. 'nice' conforms to: SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3.

Note: Windows only

proc_nice() will change the current process priority, even if PHP was compiled using thread safety.