(PHP 4, PHP 5, PHP 7)
set_time_limit — 设置脚本最大执行时间
$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。
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。
成功时返回 TRUE，失败时返回 FALSE 。
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。
if you want to check how much time remains, this should work (at least on Windows, on non-Windows platforms, i'm not sure)
$seconds_remaining_until_termination = ini_get('max_execution_time') === "0" ? null : ((int)ini_get('max_execution_time'))-(microtime(true)-$_SERVER['REQUEST_TIME_FLOAT']);
gives you number of seconds until the script will be terminated due to the time limit. (tested on Windows 7 X64 SP1 with PHP 7.3.7) - or gives you null if there is no time limit.
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 $i / 100000, "<br/>\n";
}
}
echo "done.<br/>\n";
// will echo 'done.'
?>
Both set_time_limit(...) and ini_set('max_execution_time',...); won't count the time cost of sleep,file_get_contents,shell_exec,mysql_query etc, so i build this function my_background_exec(), to run static method/function in background/detached process and time is out kill it:
my_exec.php:
<?php
function my_background_exec($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);
?>
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.
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
}
?>
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.
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);
}
?>
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);
}
?>
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.
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');
?>
If you use Apache you can change maximum execution time by .htaccess with this line
php_value max_execution_time 200
To get the currently used time, use getrusage()
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
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
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).
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
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);
$i++;
}
?>
Output:
i=0 i=1 i=2 i=3 i=4 i=5 i=6 i=7 i=8 i=9 i=10
If you are streaming large data from database, it is counted towards the max exec time.
If you set the number of seconds to a very large number (not many ppl do that, but just in case) then php exits with a fatal error like :
Fatal error: Maximum execution time of 1 second exceeded in /path/to/your/script/why.php
[EDIT by danbrown AT php DOT net: This is due to the limit of 32-bit signed integers.]
Regarding what 'nytshadow' said, it's important to realize that max-execution-time and the set_time_limit functions measure the time that the CPU is working on the script. If the script blocks, IE: for input, select, sleep, etc., then the time between blocking and returning is NOT measured. This is the same when running scripts from the command line interface. So if you've got a log parser written in PHP that tails a file, that program WILL fail eventually. It just depends how long it takes to read in enough input to process for 30 seconds.
If you're writing a command line script that should run infinitely, setting max-execution-time to 0 (never stop) is HIGHLY recommended.
this work to fine html streaming AND time pass limit
<?php
header('Content-type: text/plain');
echo date("H:m:s"), "\n";
set_time_limit(30);
for ($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";
?>
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
}
?>
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.
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.