developerfusion.com的Gringod给出了一个很好的答案:

<!-- put this at the top of the page --> 
<?php 
   $mtime = microtime(); 
   $mtime = explode(" ",$mtime); 
   $mtime = $mtime[1] + $mtime[0]; 
   $starttime = $mtime; 
;?> 

<!-- put other code and html in here -->


<!-- put this code at the bottom of the page -->
<?php 
   $mtime = microtime(); 
   $mtime = explode(" ",$mtime); 
   $mtime = $mtime[1] + $mtime[0]; 
   $endtime = $mtime; 
   $totaltime = ($endtime - $starttime); 
   echo "This page was created in ".$totaltime." seconds"; 
;?>

从(http://www.developerfusion.com/code/2058/determine-execution-time-in-php/)

developerfusion.com的Gringod给出了一个很好的答案:

<!-- put this at the top of the page --> 
<?php 
   $mtime = microtime(); 
   $mtime = explode(" ",$mtime); 
   $mtime = $mtime[1] + $mtime[0]; 
   $starttime = $mtime; 
;?> 

<!-- put other code and html in here -->


<!-- put this code at the bottom of the page -->
<?php 
   $mtime = microtime(); 
   $mtime = explode(" ",$mtime); 
   $mtime = $mtime[1] + $mtime[0]; 
   $endtime = $mtime; 
   $totaltime = ($endtime - $starttime); 
   echo "This page was created in ".$totaltime." seconds"; 
;?>

从(http://www.developerfusion.com/code/2058/determine-execution-time-in-php/)

作为一种替代方法，你可以把这一行放在你的代码块中，并检查php日志，对于非常慢的函数，它非常有用:

trigger_error("Task done at ". strftime('%H:%m:%S', time()), E_USER_NOTICE); 

严肃的调试使用XDebug + Cachegrind，请参见https://blog.nexcess.net/2011/01/29/diagnosing-slow-php-execution-with-xdebug-and-kcachegrind/

当PHP中有闭包功能时，为什么我们不从中获益呢?

function startTime(){
    $startTime = microtime(true);
    return function () use ($startTime){
        return microtime(true) - $startTime;
    };
}

现在，在上述函数的帮助下，我们可以像这样跟踪时间

$stopTime = startTime();
//some code block or line
$elapsedTime = $stopTime();

每次调用startTime函数都会启动一个单独的时间跟踪器。所以你可以想启动多少就启动多少，也可以在任何你想要的地方停止它们。

我写了一个检查剩余执行时间的函数。

警告:执行时间计数在Windows和Linux平台上是不同的。

/**
 * Check if more that `$miliseconds` ms remains
 * to error `PHP Fatal error:  Maximum execution time exceeded`
 * 
 * @param int $miliseconds
 * @return bool
 */
function isRemainingMaxExecutionTimeBiggerThan($miliseconds = 5000) {
    $max_execution_time = ini_get('max_execution_time');
    if ($max_execution_time === 0) {
        // No script time limitation
        return true;
    }
    if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
        // On Windows: The real time is measured.
        $spendMiliseconds = (microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"]) * 1000;
    } else {
        // On Linux: Any time spent on activity that happens outside the execution
        //           of the script such as system calls using system(), stream operations
        //           database queries, etc. is not included.
        //           @see http://php.net/manual/en/function.set-time-limit.php
        $resourceUsages = getrusage();
        $spendMiliseconds = $resourceUsages['ru_utime.tv_sec'] * 1000 + $resourceUsages['ru_utime.tv_usec'] / 1000;
    }
    $remainingMiliseconds = $max_execution_time * 1000 - $spendMiliseconds;
    return ($remainingMiliseconds >= $miliseconds);
}

使用:

while (true) {
    // so something

    if (!isRemainingMaxExecutionTimeBiggerThan(5000)) {
        // Time to die.
        // Safely close DB and done the iteration.
    }
}

在页面底部居中打印的小脚本，在服务器调用时以微秒精度开始脚本执行。

为了不扭曲结果，并与页面中的内容100%兼容，我使用浏览器端本地javascript代码段在页面上编写结果。

//Uncomment the line below to test with 2 seconds 
//usleep(2000000);

$prec = 5; // numbers after comma
$time = number_format(microtime(true) - $_SERVER['REQUEST_TIME_FLOAT'], $prec, '.', '');
echo "<script>
    if(!tI) { 
        var tI=document.createElement('div');
        tI.style.fontSize='8px';
        tI.style.marginBottom='5px';
        tI.style.position='absolute';
        tI.style.bottom='0px';
        tI.style.textAlign='center';
        tI.style.width='98%';
        document.body.appendChild(tI);
    }
    tI.innerHTML='$time';
</script>";

另一种方法是使代码片段尽可能小，并使用样式表中的类对其进行样式化。

替换回显…;与以下部分分开: echo "<script>if(!tI){var tI=document.createElement('div');tI. classname ='ldtme';document.body.appendChild(tI);}tI. innerhtml ='$time'; 在CSS中创建并填充.ldtme{…}类。