proc_nice
(PHP 5, PHP 7)
proc_nice — 修改当前进程的优先级
说明
$increment
) proc_nice() 修改当前进程的优先级，
修改量由 increment 参数指定。
increment 为正数会降低当前进程优先级，
反之，为负数会提高优先级。
proc_nice() 和 proc_open() 函数以及和 proc_open() 相关的函数并无什么关系。
参数
-
increment -
优先级变化值。
返回值
成功时返回 TRUE ， 或者在失败时返回 FALSE 。。
如果发生错误，例如用户无权修改当前进程的优先级，
会生成 E_WARNING 级别的错误。
注释
Note: Availability
仅在具有 'nice' 能力的系统上才可以使用 proc_nice() 函数。 下列系统含有 'nice'：SVr4, SVID EXT, AT&T, X/OPEN, BSD 4.3。 也就是说，此函数在 Windows 平台上不可用。
用户评论:
[#1] kevin AT REMOVETHIS mrkmg.com [2013-04-19 18:17:38]
On a Linux system, running apache2 as a non-privileged user you can not increase the niceness of the process after decreasing it. Also, you can not use the apache_child_ terminate either. I found the following does work though:
<?php
//decrease niceness
proc_nice(19);
//kill child process to "reset" niceness
posix_kill( getmypid(), 28 );
?>
[#2] Marek [2011-01-19 08:40:43]
Regarding ionice - on linux the impact of the ionice -c3 class is similar to that of nice, because the CPU "niceness" is taken into account when calculating the io niceness.
[#3] php at richardneill dot org [2010-06-24 00:14:34]
If a process is reniced, then all its children inherit that niceness. So a PHP script can call proc_nice on itself, then invoke system(), and the command executed via system() will also be niced.
Also worth making a note of ionice. There's no PHP function for this, but it's important. A nice'd program will happily try to chew up all i/o bandwidth with very little CPU usage, it can therefore make the entire computer non-responsive despite the programmer's intention. Use "ionice -c3" or see "man ionice"
[#4] pandi at home dot pl [2008-11-25 05:22:11]
Simple function for check process nice, by default returns nice of current process:
<?php
public static function getProcessNice ($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]) ? $matches[2] : null));
}
?>
[#5] griph at dd dot chalmer dot se [2003-11-10 14:34:52]
If you don't have PHP5 and needs to nice your process this works good.
<?php
function proc_nice($priority) {
exec("renice +$priority ".getmypid());
}
//You also need a shutdown function if you don't want to leave your http deamons with a modified priority
function exit_func(){
// Restore priority
proc_nice(0);
}
register_shutdown_function('exit_func');
?>