(PHP 5, PHP 7, PHP 8)
proc_nice — Modificar la prioridad del proceso actual
proc_nice() modifica la prioridad del proceso
actual por la cantidad especificada en
increment. Un
increment positivo reducirá la
prioridad del proceso actual, mientras que un
increment negativo la incrementará.
proc_nice() no está relacionada con proc_open() y sus funciones asociadas en ninguna forma.
incrementEl valor de incremento del cambio de prioridad.
Devuelve true en caso de éxito o false en caso de error. Si ocurre un error, como que el usuario carezca de
permisos para modificar la prioridad, un error de nivel
E_WARNING es generado también.
Nota: Disponibilidad
proc_nice() existirá únicamente si su sistema tiene soporte para 'nice'. 'nice' está definido de acuerdo a los estándares: SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3. Esto quiere decir que proc_nice() no está disponible en Windows.
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 nicenessproc_nice(19);//kill child process to "reset" nicenessposix_kill( getmypid(), 28 );?>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"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.It is important to note that this is a relative change. I didn't read the description properly and couldn't figure out why setting proc_nice(0) didn't take the forked children back to 0!For example if you run:<?phpproc_nice(-5);proc_nice(0); // will have no effectproc_nice(5); // will take the niceness back to 0 ?>In PHP CLI under Debian (and probably many other Linux flavours) you can read the 'niceness' from the proc filesystem. (There may be a PHP command that gives this info but there doesn't seem to be a link to it on this page.)E.g<?php$Current_Niceness_Value = intval(explode(" ",file_get_contents("/proc/".getmypid()."/stat"))[18]);// Note: Older versions of Linux return an unsigned integer which has to be converted to a signed integer. $Current_Niceness_Value = unpack("l",pack("L",intval(explode(" ",file_get_contents("/proc/".getmypid()."/stat"))[18])))[1];?>Simple function for check process nice, by default returns nice of current process:<?phppublic static function getProcessNice ($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));}?>