PHP 7.0.14 Released

proc_nice

(PHP 5, PHP 7)

proc_niceChange the priority of the current process

Descrizione

bool proc_nice ( int $increment )

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

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

Elenco dei parametri

increment

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 increment parameter have the following meanings:

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

Valori restituiti

Restituisce TRUE in caso di successo, FALSE in caso di fallimento. If an error occurs, like the user lacks permission to change the priority, an error of level E_WARNING is also generated.

Esempi

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

<?php
// Highest priority
proc_nice(-20)
?>

Log delle modifiche

Versione Descrizione
7.2.0 This function is now available on Windows.

Note

Nota: 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.

Nota: Windows only

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

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User Contributed Notes 4 notes

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6
kevin AT REMOVETHIS mrkmg.com
3 years ago
On a Linux system, running apache2 as a non-privileged user you can not increase the niceness of the process after decreasing it. Also, you can not use the apache_child_ terminate either. I found the following does work though:

<?php

//decrease niceness
proc_nice(19);

//kill child process to "reset" niceness
posix_kill( getmypid(), 28 );

?>
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2
php at richardneill dot org
6 years ago
If a process is reniced, then all its children inherit that niceness. So a PHP script can call proc_nice on itself, then invoke system(), and the command executed via system() will also be niced.

Also worth making a note of ionice. There's no PHP function for this, but it's important. A nice'd program will happily try to chew up all i/o bandwidth with very little CPU usage, it can therefore make the entire computer non-responsive despite the programmer's intention.  Use "ionice -c3"  or see "man ionice"
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2
Marek
5 years ago
Regarding ionice - on linux the impact of the ionice -c3 class is similar to that of nice, because the CPU "niceness" is taken into account when calculating the io niceness.
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1
pandi at home dot pl
8 years ago
Simple function for check process nice, by default returns nice of current process:

<?php

public static function getProcessNice ($pid = null) {
    if (!
$pid) {
       
$pid = getmypid ();
    }
       
   
$res = `ps -p $pid -o "%p %n"`;
       
   
preg_match ('/^\s*\w+\s+\w+\s*(\d+)\s+(\d+)/m', $res, $matches);
       
    return array (
'pid' => (isset ($matches[1]) ? $matches[1] : null), 'nice' => (isset ($matches[2]) ? $matches[2] : null));
}

?>
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