php教程

set_time_limit

(PHP 4, PHP 5, PHP 7)

set_time_limit — 设置脚本最大执行时间

说明

set_time_limit ( int $seconds ) : bool

设置允许脚本运行的时间，单位为秒。如果超过了此设置，脚本返回一个致命的错误。默认值为30秒，或者是在php.ini的max_execution_time被定义的值，如果此值存在。

当此函数被调用时，set_time_limit()会从零开始重新启动超时计数器。换句话说，如果超时默认是30秒，在脚本运行了了25秒时调用 set_time_limit(20)，那么，脚本在超时之前可运行总时间为45秒。

参数

seconds

最大的执行时间，单位为秒。如果设置为0（零），没有时间方面的限制。

返回值

成功时返回 TRUE，失败时返回 FALSE 。

注释

Warning

当php运行于安全模式时，此功能不能生效。除了关闭安全模式或改变php.ini中的时间限制，没有别的办法。

Note:

set_time_limit()函数和配置指令max_execution_time只影响脚本本身执行的时间。任何发生在诸如使用system()的系统调用，流操作，数据库操作等的脚本执行的最大时间不包括其中，当该脚本已运行。在测量时间是实值的Windows中，情况就不是如此了。

User Contributed Notes

f.nakamura 06-Jul-2015 07:54
set_tme_limit resets the execution time count.

test code1:
<?php
echo '<html><body>';
set_time_limit(1);
$i = 0;
while(++$i < 100000001){
        if($i % 100000 == 0){
                echo $i / 100000, "<br/>\n";
        }
}
echo "done.<br/>\n";

// will not echo 'done.'.
?>

test code2:
<?php
echo '<html><body>';
set_time_limit(1);
$i = 0;
while(++$i < 100000001){
        if($i % 100000 == 0){
                set_time_limit(1);
                echo $i / 100000, "<br/>\n";
        }
}
echo "done.<br/>\n";

// will echo 'done.'
?>
kexianbin at diyism dot com 20-May-2014 09:41
Both set_time_limit(...) and  ini_set('max_execution_time',...); won't count the time cost of sleep,file_get_contents,shell_exec,mysql_query etc, so i build this function my_background_exec(), to run static method/function in background/detached process and time is out kill it:

my_exec.php:
<?php
function my_background_exec($function_name, $params, $str_requires, $timeout=600)
         {$map=array('"'=>'\"', '$'=>'\$', '`'=>'\`', '\\'=>'\\\\', '!'=>'\!');
          $str_requires=strtr($str_requires, $map);
          $path_run=dirname($_SERVER['SCRIPT_FILENAME']);
          $my_target_exec="/usr/bin/php -r \"chdir('{$path_run}');{$str_requires} \\\$params=json_decode(file_get_contents('php://stdin'),true);call_user_func_array('{$function_name}', \\\$params);\"";
          $my_target_exec=strtr(strtr($my_target_exec, $map), $map);
          $my_background_exec="(/usr/bin/php -r \"chdir('{$path_run}');{$str_requires} my_timeout_exec(\\\"{$my_target_exec}\\\", file_get_contents('php://stdin'), {$timeout});\" <&3 &) 3<&0";//php by default use "sh", and "sh" don't support "<&0"
          my_timeout_exec($my_background_exec, json_encode($params), 2);
         }

function my_timeout_exec($cmd, $stdin='', $timeout)
         {$start=time();
          $stdout='';
          $stderr='';
          //file_put_contents('debug.txt', time().':cmd:'.$cmd."\n", FILE_APPEND);
          //file_put_contents('debug.txt', time().':stdin:'.$stdin."\n", FILE_APPEND);

          $process=proc_open($cmd, [['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']], $pipes);
          if (!is_resource($process))
             {return array('return'=>'1', 'stdout'=>$stdout, 'stderr'=>$stderr);
             }
          $status=proc_get_status($process);
          posix_setpgid($status['pid'], $status['pid']);    //seperate pgid(process group id) from parent's pgid

          stream_set_blocking($pipes[0], 0);
          stream_set_blocking($pipes[1], 0);
          stream_set_blocking($pipes[2], 0);
          fwrite($pipes[0], $stdin);
          fclose($pipes[0]);

          while (1)
                {$stdout.=stream_get_contents($pipes[1]);
                 $stderr.=stream_get_contents($pipes[2]);

                 if (time()-$start>$timeout)
                    {//proc_terminate($process, 9);    //only terminate subprocess, won't terminate sub-subprocess
                     posix_kill(-$status['pid'], 9);    //sends SIGKILL to all processes inside group(negative means GPID, all subprocesses share the top process group, except nested my_timeout_exec)
                     //file_put_contents('debug.txt', time().":kill group {$status['pid']}\n", FILE_APPEND);
                     return array('return'=>'1', 'stdout'=>$stdout, 'stderr'=>$stderr);
                    }

                 $status=proc_get_status($process);
                 //file_put_contents('debug.txt', time().':status:'.var_export($status, true)."\n";
                 if (!$status['running'])
                    {fclose($pipes[1]);
                     fclose($pipes[2]);
                     proc_close($process);
                     return $status['exitcode'];
                    }

                 usleep(100000);
                }
         }
?>

a_class.php:
<?php
class A
{
    static function jack($a, $b)
           {sleep(4);
            file_put_contents('debug.txt', time().":A::jack:".$a.' '.$b."\n", FILE_APPEND);
            sleep(15);
           }
}
?>

test.php:
<?php
require 'my_exec.php';

my_background_exec('A::jack', array('hello', 'jack'), 'require "my_exec.php";require "a_class.php";', 8);
?>
robertbrogers at gmail dot com 09-Jan-2014 08:45
Documentation states:
When called, set_time_limit() restarts the timeout counter from zero. In other words, if the timeout is the default 30 seconds, and 25 seconds into script execution a call such as set_time_limit(20) is made, the script will run for a total of 45 seconds before timing out.

If I have a long running script and i want a exact  time limit, I set this as near as possible to the first line.
mingalevme at gmail dot com 10-May-2012 07:51
If you're using PHP_CLI SAPI and getting error "Maximum execution time of N seconds exceeded" where N is an integer value, try to call set_time_limit(0) every M seconds or every iteration. For example:

<?php

require_once('db.php');

$stmt = $db->query($sql);

while ($row = $stmt->fetchRow()) {
    set_time_limit(0);
    // your code here
}

?>
ratty at brohoof dot com 25-Nov-2011 07:39
One thing that I wish I had found sooner is, if you're using php-cli and really need to limit the executation time, and if you're in *nix, you can use "timeout" which is part of coreutils.
For example:

timeout 5 /usr/bin/php -q /path/to/script

and it will kill it if it takes longer than 5 seconds.
I had a few quick php scripts I wrote for use with cacti for example.
alexander dot krause at ed-solutions dot de 29-Aug-2011 02:26
A nice workaround to have a real max_execution_time (needs posix and pcntl):

<?php
$pid=pcntl_fork();

if ($pid) {
  //long time process
  $a=0;
  while (true) {
    echo "a=$a\n\n";
    ob_flush();
    flush();
    $a++;
    shell_exec('sleep 10&');
  }
} else {
  //time-limit checker
  sleep(5);
  posix_kill(posix_getppid(),SIGKILL);
}
?>
agvozden at gmail dot com 01-Oct-2010 01:51
If you got something like:

msg: set_time_limit() [function.set-time-limit]: Cannot set time limit in safe mode

try this:

<?php
        if( !ini_get('safe_mode') ){
            set_time_limit(25);
        }
?>
Silver_Knight 23-Mar-2010 05:18
if you are running a script that needs to execute for unknown time, or forever.. you may use
set_time_limit(0);
.....
...
..
.
and at the end of the script use flush() function to tell phpto send out what it has generated.
ravenswd at gmail dot com 15-Aug-2009 04:46
Unfortunately, a script which gets into an infinite loop can produce an alarming amount of output in only a few seconds. I was attempting to debug a script, and I added

<?php
set_time_limit(2);
?>

to the beginning of the script. Unfortunately, even two seconds of run time produced enough output to overload the memory available to my browser.

So, I wrote a short routine which would limit the execution time, and also limit the amount of output returned. I added this to the beginning of my script and it worked perfectly:

<?php
set_time_limit(2);

ob_start();     // buffer output

function shutdown () {
    // print only first 2000 characters of output
    $out = ob_get_clean();
    print substr($out, 0, 2000);
}

register_shutdown_function('shutdown');
?>
BW 16-May-2009 05:08
If you use Apache you can change maximum execution time by .htaccess with this line

php_value max_execution_time 200
cweiske at cweiske dot de 02-Sep-2008 04:38
To get the currently used time, use getrusage()
jonathon dot keogh at gmail dot com 18-Jul-2008 02:07
You can do set_time_limit(0); so that the script will run forever - however this is not recommended and your web server might catch you out with an imposed HTTP timeout (usually around 5 minutes).

You should check your web server's guides for more information about HTTP timeouts.

Jonathon
AtlantisNet 04-Jun-2008 12:08
In IIS, there is another global timeout setting which will override any PHP settings.  You can alter this timeout by following the following instructions:

http://www.iisadmin.co.uk/?p=7
php at stock-consulting dot com 12-Jan-2007 05:30
To find out the currently set time limit, use

<?php
 ini_get('max_execution_time');
?>

If set_time_limit has been previously called in the script, the result will be the value which was passed to set_time_limit (and not, as the function name "ini_get" appears to suggest, the value from the php.ini file).
bjfieldNO at SPAMgmail dot com 10-Jan-2007 02:53
Timeouts after five minutes in IIS on Windows are caused by an inherited CGI Timeout value of 300 seconds.  This is not a PHP problem.  The fix is to add custom values for the files or directories that need longer to run.

In IIS 5.0 or 7.0 (beta as of this note), you can change this value on a fairly granular level using IIS Manager, under (roughly) YOURSITE -> Properties -> Home Directory -> Configuration (button) -> Options, but in IIS 6.0, this functionality is turned off (!), so you have to get into the Metabase.

Find the site number in Metabase Explorer (e.g., 12345678), then from CMD prompt:

[get to the scripts dir]
cd C:\Inetpub\AdminScripts

[this for each subdirectory from off the site root]
cscript adsutil.vbs CREATE W3SVC/12345678/root/"MY SUBDIRECTORY" IIsWebDirectory

[this for the file in question]
cscript adsutil.vbs CREATE W3SVC/12345678/root/"MY SUBDIRECTORY"/ILikeToTimeOut.php IIsWebFile

[this to set the timeout]
cscript adsutil.vbs set W3SVC/12345678/root/"MY SUBDIRECTORY"/ILikeToTimeOut.php/CGITimeout "7200"

Note:  "7200" is 2 hours in seconds, but can be whatever.

I derived the solution above from this fine article:
http://www.iis-resources.com/modules/AMS/article.php?
storyid=509&page=3
mba_aslam at yahoo dot com 05-Jan-2007 05:50
while setting the set_time_limit(), the duration of sleep() will be ignored in the execution time. The following illustrates:

<?php

set_time_limit(20);

while ($i<=10)
{
        echo "i=$i ";
        sleep(100);
        $i++;
}

?>

Output:
i=0 i=1 i=2 i=3 i=4 i=5 i=6 i=7 i=8 i=9 i=10
konrads dot smelkovs at gmail dot com 01-Apr-2006 06:35
If you are streaming large data from database, it is counted towards the max exec time.
jatin at jatinchimote dot com 01-Mar-2006 10:54
If you set the number of seconds to a very large number (not many ppl do that, but just in case) then php exits with a fatal error like :

Fatal error: Maximum execution time of 1 second exceeded in /path/to/your/script/why.php

[EDIT by danbrown AT php DOT net: This is due to the limit of 32-bit signed integers.]
Cleverduck 28-Feb-2006 01:36
Regarding what 'nytshadow' said, it's important to realize that max-execution-time and the set_time_limit functions measure the time that the CPU is working on the script.  If the script blocks, IE: for input, select, sleep, etc., then the time between blocking and returning is NOT measured.  This is the same when running scripts from the command line interface.  So if you've got a log parser written in PHP that tails a file, that program WILL fail eventually.  It just depends how long it takes to read in enough input to process for 30 seconds.

If you're writing a command line script that should run infinitely, setting max-execution-time to 0 (never stop) is HIGHLY recommended.
rycardo74 at gmail dot com 24-Nov-2005 10:52
this work to fine html streaming AND time pass limit

<?php
header('Content-type: text/plain');
echo date("H:m:s"), "\n";
set_time_limit(30);
for ($i = 0; $i < 1000; $i++)
{

    echo date("H:m:s"),"\n";
    for ($r = 0; $r < 100000; $r++){
    $X.=  tan(M_LNPI+log(ceil(  date("s")*M_PI*M_LNPI+100)));
    }
    ob_flush();  
    flush();

}
echo "work! $x";
?>
eric pecoraro at shepard com 06-Jun-2005 12:57
I was having trouble with script timeouts in applications where the user prompted long running background actions. I wrote this cURL/CLI background script that solved the problem when making requests from HTTP.

<?php

/* BACKGROUND CLI 1.0
  
   eric pecoraro _at_ shepard dot com - 2005-06-02
   Use at your own risk. No warranties expressed or implied.

   Include this file at the top of any script to run it in the background
   with no time limitations ... e.g., include('background_cli.php');
  
   The script that calls this file should not return output to the browser.
*/
#  REQUIREMENTS - cURL and CLI
   if ( !function_exists('curl_setopt') OR !function_exists('curl_setopt')  ) {
      echo 'Requires cURL and CLI installations.' ; exit ;
   }
  
#  BUILD PATHS
   $script = array_pop(explode('/',$SCRIPT_NAME)) ;
   $script_dir = substr($SCRIPT_NAME,0,strlen($SCRIPT_NAME)-strlen($script)) ;
   $scriptURL = 'http://'. $HTTP_HOST . $script_dir . "$script" ;
   $curlURL = 'http://'. $HTTP_HOST . $script_dir . "$script?runscript=curl" ;

#  Indicate that script is being called by CLI
   if ( php_sapi_name() == 'cli' ) {
      $CLI = true ;
   }

#  Action if script is being called by cURL_prompt()
   if ( $runscript == 'curl' ) {
      $cmd = "/usr/local/bin/php ".$PATH_TRANSLATED ; // server location of script to run
      exec($cmd) ;
      exit;
   }

#  USER INTERFACE
   // User answer after submission.
   if ( $post ) {
      cURL_prompt($curlURL) ;
      echo '<div style="margin:25px;"><title>Background CLI</title>';
      echo 'O.K. If all goes well, <b>'.$script.'</b> is working hard in the background with no ' ;
      echo 'timeout limitations. <br><br><form action='.$scriptURL.' method=GET>' ;
      echo '<input type=submit value=" RESET BACKGROUND CLI "></form></div>' ;
      exit ;
   }
   // Start screen.
   if ( !$CLI AND !$runscript ) {
      echo '<title>Background CLI</title><div style="margin:25px;">' ;
      echo '<form action='.$scriptURL.' method=POST>' ;
      echo 'Click to run <b>'.$script.'</b> from the PHP CLI command line, in the background.<br><br>' ;
      echo '<input type=hidden value=1 name=post>' ;
      echo '<input type=submit value=" RUN IN BACKGROUND "></form></div>' ;
      exit ;
   }

#  cURL URL PROMPT FUNCTION
   function cURL_prompt($url_path) {
      ob_start(); // start output buffer
      $c=curl_init($url_path);
      curl_setopt($c, CURLOPT_TIMEOUT, 2); // drop connection after 2 seconds
      curl_exec($c);
      curl_close($c);
      ob_end_clean(); // discard output buffer
   }
?>
php at mightycpa.com 26-Jun-2003 01:30
You may also need to look at Apache's timeout setting (Win32 version for me), I changed max execution time value in php.ini, and still got stopped by Apache's timeout value in the httpd.conf file.
rsallo at gna dot NOSPAM dot es 30-May-2003 04:28
When you are working with IIS, PHP timeout is valid only when it's lower than script timeout defined by IIS.

IIS 5 has a default timeout of 300 seconds. If you need a higher timeout, you also have to change IIS properties. Otherwise, your server will stop your PHP script before it reaches its own timeout.

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