这里列出了几种方法。但每个人都有自己的优点和缺点。而且(在我看来)所有较长的答案的可读性都很糟糕。

所以我决定把这些都放在一个答案中，这是容易使用和阅读的。

使用

$start = get_timers();
for( $i = 0; $i < 100000; $i++ ){
  // Code to check
}
$end = get_timers();
display_timer_statistics( $start, $end );

函数定义

function display_timer_statistics( $start_timers, $end_timers ){

    // Settings
    $key_width = '100px';
    $decimals = 4;
    $decimals_wallclock = $decimals;
    $decimals_request_time_float = $decimals;

    // Variables
    $start_resource_usage_timer = $start_timers[0];
    $start_wallclock = $start_timers[1];
    $end_resource_usage_timer = $end_timers[0];
    $end_wallclock = $end_timers[1];

    // # User time
    // Add seconds and microseconds for the start/end, and subtract from another
    $end_user_time_seconds = $end_resource_usage_timer["ru_utime.tv_sec"]*1000;
    $end_user_time_microseconds = intval($end_resource_usage_timer["ru_utime.tv_usec"]/1000);
    $start_user_time_seconds = $start_resource_usage_timer["ru_utime.tv_sec"]*1000;
    $start_user_time_microseconds = intval($start_resource_usage_timer["ru_utime.tv_usec"]/1000);
    $total_user_time = ($end_user_time_seconds + $end_user_time_microseconds) - ($start_user_time_seconds + $start_user_time_microseconds);

    // # System time
    // Add seconds and microseconds for the start/end, and subtract from another
    $end_system_time_seconds = $end_resource_usage_timer["ru_stime.tv_sec"]*1000;
    $end_system_time_microseconds = intval($end_resource_usage_timer["ru_stime.tv_usec"]/1000);
    $start_system_time_seconds = $start_resource_usage_timer["ru_stime.tv_sec"]*1000;
    $start_system_time_microseconds = intval($start_resource_usage_timer["ru_stime.tv_usec"]/1000);
    $total_system_time = ($end_system_time_seconds + $end_system_time_microseconds) - ($start_system_time_seconds + $start_system_time_microseconds);

    // Wallclock
    $total_wallclock_time = number_format( ( $end_wallclock - $start_wallclock), $decimals_wallclock );

    // Server request_time_float
    $request_time_float = microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"];
    $request_time_float = number_format( $request_time_float, $decimals_request_time_float );

    // Print
    $span_start = "<span style='width: $key_width; display: inline-block;'>";
    $span_end = "</span>";

    $output = "# RUNTIME AND TIMERS " . PHP_EOL ;
    $output .= PHP_EOL;
    $output .= $span_start . $total_user_time . $span_end . " User time (utime)" . PHP_EOL;
    $output .= $span_start . $total_system_time . $span_end . " System time (stime)" . PHP_EOL;
    $output .= PHP_EOL;
    $output .= $span_start . $total_wallclock_time . $span_end . " Wallclock" . PHP_EOL;
    $output .= PHP_EOL;
    $output .= $span_start . $request_time_float . $span_end . " REQUEST_TIME_FLOAT" . PHP_EOL . PHP_EOL . PHP_EOL;

    echo nl2br( $output );
}

function get_timers(){
    return [ getrusage(), microtime( true ) ];
}

术语表

这些都是从PHP文档中获取的

挂钟=花了多长时间 ru =资源使用率 utime =用户使用的时间 stime =使用的系统时间 tv_sec =秒。 tv_usec =以微秒计。 电视= ??不知道

最便宜也是最麻烦的方法是在代码中想要进行基准测试的地方进行microtime()调用。在数据库查询之前和之后执行它，从脚本执行时间的其余部分中删除这些持续时间就很简单了。

提示:PHP执行时间很少会导致脚本超时。如果一个脚本超时，它几乎总是调用外部资源。

PHP微时间文档: http://us.php.net/microtime

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.
    }
}

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/)

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。

在unix系统上(在Windows上的php 7+中也是如此)，你可以使用getrusage，像这样:

// Script start
$rustart = getrusage();

// Code ...

// Script end
function rutime($ru, $rus, $index) {
    return ($ru["ru_$index.tv_sec"]*1000 + intval($ru["ru_$index.tv_usec"]/1000))
     -  ($rus["ru_$index.tv_sec"]*1000 + intval($rus["ru_$index.tv_usec"]/1000));
}

$ru = getrusage();
echo "This process used " . rutime($ru, $rustart, "utime") .
    " ms for its computations\n";
echo "It spent " . rutime($ru, $rustart, "stime") .
    " ms in system calls\n";

注意，如果要为每个测试生成一个php实例，则不需要计算差异。