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microtime

(PHP 4, PHP 5, PHP 7)

microtime — 返回当前 Unix 时间戳和微秒数

说明

mixed microtime ([ bool $get_as_float ] )

microtime() 当前 Unix 时间戳以及微秒数。本函数仅在支持 gettimeofday() 系统调用的操作系统下可用。

如果调用时不带可选参数，本函数以 "msec sec" 的格式返回一个字符串，其中 sec 是自 Unix 纪元（0:00:00 January 1, 1970 GMT）起到现在的秒数，msec 是微秒部分。字符串的两部分都是以秒为单位返回的。

如果给出了 get_as_float 参数并且其值等价于 TRUE ， microtime() 将返回一个浮点数。

Note: get_as_float 参数是 PHP 5.0.0 新加的。

Example #1 用 microtime() 对脚本的运行计时

  <?php
 
 function  microtime_float ()
{
    list( $usec ,  $sec ) =  explode ( " " ,  microtime ());
    return ((float) $usec  + (float) $sec );
}

 $time_start  =  microtime_float ();

 // Sleep for a while
 usleep ( 100 );

 $time_end  =  microtime_float ();
 $time  =  $time_end  -  $time_start ;

echo  "Did nothing in  $time  seconds\n" ;
 ?>

参见 time() 。

用户评论:

[#1] krzysiekpiasecki at gmail dot com [2015-09-29 16:59:41]

Microtime as float in a functional way

<?php array_reduce( explode(" ", microtime), function($time, $microtime) { return $microtime + (float) $time; }, 0.0 ); ?>

[#2] JumpIfBelow [2015-03-30 14:16:15]

To know how much time a code need to execute, I use my own class which I defined like this :

<?php class RenderTime{ const PRECISION_SECOND = 0; const PRECISION_MILLISECOND = 1; const PRECISION_MICROSECOND = 2; private $start; private $end; public function __construct(){ $this->start = null; $this->end = null; } public function start(){ $this->start = microtime(true); $this->end = null; } public function end(){ $this->end = microtime(true); } public function getRenderTime($precision = self::PRECISION_SECOND, $floatingPrecision = 0, $showUnit = true){ $test = is_int($precision) && $precision >= self::PRECISION_SECOND && $precision <= self::PRECISION_MICROSECOND && is_float($this->start) && is_float($this->end) && $this->start <= $this->end && is_int($floatingPrecision) && $floatingPrecision >= 0 && is_bool($showUnit); if($test){ $duration = round(($this->end - $this->start) * 10 ** ($precision * 3), $floatingPrecision); if($showUnit) return $duration.' '.self::getUnit($precision); else return $duration; }else{ return 'Can\'t return the render time'; } } private static function getUnit($precision){ switch($precision){ case self::PRECISION_SECOND : return 's'; case self::PRECISION_MILLISECOND : return 'ms'; case self::PRECISION_MICROSECOND : return '?s'; default : return '(no unit)'; } } } ?>
If you want to use it, it's quiet simple:

<?php $render_time = new RenderTime(); $render_time->start(); for($i = 0; $i < 2 ** 24; $i++){} $render_time->end(); echo 'Time to render: '.$render_time->getRenderTime(RenderTime::PRECISION_MILLISECOND); ?>

It should output somthing like this : 'Time to render: 3029 ms'
Very useful for quick optimisation

[#3] Endy from 281591 at qq dot com [2014-12-15 05:40:42]

Following are tested under PHP 5.6.2:
microtime() returns a string in the form "msec.sec" not "msec sec".

So in Example #1, this line should be
list ($usec, $sec) = explode(".", $e);

[#4] Daniel Rhodes [2013-08-27 12:54:39]

But note that the default 'precision' setting of PHP* - which is used when a float is converted to a stringy format by echo()ing, casting or json_encode()ing etc - is not enough to hold the six digit accuracy of microtime(true).

Out of the box, microtime(true) will echo something like:

1377611450.1234

Which is obviously less than microsecond accuracy. You'll probably want to bump the 'precision' setting up to 16 which will echo something like:

1377611450.123456

*Internally* it will be accurate to the six digits even with the default 'precision', but a lot of things (ie. NoSQL databases) are moving to all-text representations these days so it becomes a bit more important.

* 14 at the time of writing

[#5] Nads [2013-07-17 08:28:26]

Get date time with milliseconds

$micro_date = microtime();
$date_array = explode(" ",$micro_date);
$date = date("Y-m-d H:i:s",$date_array[1]);
echo "Date: $date:" . $date_array[0];

Test accuracy by running it in a loop.

[#6] Russell G. [2013-05-03 20:34:32]

Note that the timestamp returned is "with microseconds", not "in microseconds". This is especially good to know if you pass 'true' as the parameter and then calculate the difference between two float values -- the result is already in seconds; it doesn't need to be divided by a million.

[#7] player27 [2013-01-15 16:31:55]

You can use one variable to check execution $time as follow:

<?php $time = -microtime(true); $hash = 0; for ($i=0; $i < rand(1000,4000); ++$i) { $hash ^= md5(substr(str_shuffle("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, rand(1,10))); } $time += microtime(true); echo "Hash: $hash iterations:$i time: ",sprintf('%f', $time),PHP_EOL; ?>

[#8] Anonymous [2012-08-24 15:34:50]

Observed in php 5.3.3 on CentOS 6 and php 5.3.14 on Amazon Linux 2012.03:

microtime()'s string value is in the format "0.dddddd00 ddddd...". That is, there's room for 10-ns precision that isn't being used, and the "msec" value is in decimal, not a literal number of microseconds (and *especially* not milliseconds, which is what msec usually stands for) as the documentation might imply.

[#9] thomas [2012-04-12 02:45:26]

I have been getting negative values substracting a later microtime(true) call from an earlier microtime(true) call on Windows with PHP 5.3.8

Produces negative values
------------------------------
for($i = 0; $i<100; $i++) {
$x = microtime(true);
//short calculation
$y = microtime(true);
echo ($y-$x) . "\n"; // <--- mostly negatives
}

Calling usleep(1) seems to work
---------------------------------------
for($i = 0; $i<100; $i++) {
$x = microtime(true);
//short calculation
usleep(1);
$y = microtime(true);
echo ($y-$x) . "\n"; // <--- fixed now
}

[#10] langpavel at phpskelet dot org [2011-05-19 13:46:22]

I use this for measure duration of script execution. This function should be defined (and of couse first call made) as soon as possible.

<?php function get_execution_time() { static $microtime_start = null; if($microtime_start === null) { $microtime_start = microtime(true); return 0.0; } return microtime(true) - $microtime_start; } get_execution_time(); ?>

However it is true that result depends of gettimeofday() call. ([jamie at bishopston dot net] wrote this & I can confirm)
If system time change, result of this function can be unpredictable (much greater or less than zero).

[#11] jamie at bishopston dot net [2010-12-30 12:55:30]

All these timing scripts rely on microtime which relies on gettimebyday(2)

This can be inaccurate on servers that run ntp to syncronise the servers
time.

For timing, you should really use clock_gettime(2) with the
CLOCK_MONOTONIC flag set.

This returns REAL WORLD time, not affected by intentional clock drift.

This may seem a bit picky, but I recently saw a server that's clock was an
hour out, and they'd set it to 'drift' to the correct time (clock is speeded
up until it reaches the correct time)

Those sorts of things can make a real impact.

Any solutions, seeing as php doesn't have a hook into clock_gettime?

More info here: http://tinyurl.com/28vxja9

http://blog.habets.pp.se/2010/09/
gettimeofday-should-never-be-used-to-measure-time

[#12] Robin Leffmann [2010-12-24 12:07:55]

While doing some experiments on using microtime()'s output for an entropy generator I found that its microsecond value was always quantified to the nearest hundreds (i.e. the number ends with 00), which affected the randomness of the entropy generator. This output pattern was consistent on three separate machines, running OpenBSD, Mac OS X and Windows.

The solution was to instead use gettimeofday()'s output, as its usec value followed no quantifiable pattern on any of the three test platforms.

[#13] Anonymous [2010-09-23 21:53:42]

that related to the prescedence of the . operator

<?php
# normal prescedence
$a = "te" . 1 - 2 . "st"; # ((te . 1) - 2 ) . st ==> -2st
$b = "te" . 1 + 2 . "st"; # ((te . 1) + 2 ) . st ==> 2st

# modified prescedence
$c = "te" . ( 1 - 2 ) . "st"; # te . ( 1 - 2 ) . st ==> te-1st
$d = "te" . ( 1 + 2 ) . "st"; # te . ( 1 + 2 ) . st ==> te3st

var_dump( $a, $b );
var_dump( $c, $d );

[#14] Andris [2010-08-10 02:23:56]

I wrote a class which allows to time execution of php scripts very easily. You can even time multiple separate blocks and then get the total time at the end.

The class is pretty long so I won't post it here, but here's the link:
http://codeaid.net/php/calculate-script-execution-time-(php-class)

An quick usage example:
<?php for ($i = 0; $i < 100; $i++) { // calculate the time it takes to run fx() Timer::start(); fx(); Timer::stop(); fy(); // calculate the time it takes to run fz() Timer::start(); fz(); Timer::stop(); } print Timer::get(); ?>

[#15] bleakwind at gmail dot com [2009-09-16 10:19:26]

Check Program runtime:
<?php class bwruntime { var $timestart; var $digits; function bwruntime($digits = "") { $this->timestart = explode (' ', microtime()); $this->digits = $digits; } function totaltime() { $timefinish = explode (' ', microtime()); if($this->digits == ""){ $runtime_float = $timefinish[0] - $this->timestart[0]; }else{ $runtime_float = round(($timefinish[0] - $this->timestart[0]), $this->digits); } $runtime = ($timefinish[1] - $this->timestart[1]) + $runtime_float; return $runtime; } } ?>

[#16] thawootah [2009-08-02 16:23:33]

Want to make sure your script doesn't time out on large updates? Say you're doing a poor mans cron job or working with large amounts of data in loop and the user begins to hang too long. Instead of them giving up and leaving you can break the loop when it reaches a set time and still display data.

Here's a simple handy dandy loop timer rounded to second.
<?php $starttime = round(microtime(true)); $totaltime = 0; $maxtime = 5; //seconds for ($i = 1; $i <= 20; $i++) { /// 20 loops 1 sec each usleep(1000000); if($totaltime < $maxtime){ $currenttime = round(microtime(true)); $totaltime = $totaltime + ($currenttime -$starttime); //update and continue echo $i.'<br>'; }else{ // stop updating or display not updated data. break; } } ?>

[#17] gomodo at free dot fr [2009-06-17 03:32:45]

Need a mini benchmark ?
Use microtime with this (very smart) benchmark function :

mixed mini_bench_to(array timelist[, return_array=false])
return a mini bench result

-the timelist first key must be 'start'
-default return a resume string, or array if return_array= true :
'total_time' (ms) in first row
details (purcent) in next row

example :
<?php unset($t);    // if previous used //-- zone to bench $t['start'] = microtime(true); $tab_test=array(1,2,3,4,5,6,7,8); $fact=1; $t['init_values'] = microtime(true); foreach ($tab_test as $key=>$value) {     $fact=$fact*$value; } $t['loop_fact'] = microtime(true); echo "fact = ".$fact."\n"; //-- END zone to bench echo "---- string result----\n"; $str_result_bench=mini_bench_to($t); echo $str_result_bench; // string return echo "---- tab result----\n"; $tab_result_bench=mini_bench_to($t,true); echo var_export($tab_result_bench,true); ?>
this example return:

---- string result----
total time : 0.0141 ms
start -> init_values : 51.1 %
init_values -> loop_fact : 48.9 %
---- tab result----
array (
  'total_time' => 0.0141,
  'start -> init_values' => 51.1,
  'init_values -> loop_fact' => 48.9,
)

The function to include :

<?php function mini_bench_to($arg_t, $arg_ra=false)   {     $tttime=round((end($arg_t)-$arg_t['start'])*1000,4);     if ($arg_ra) $ar_aff['total_time']=$tttime;     else $aff="total time : ".$tttime."ms\n";     $prv_cle='start';     $prv_val=$arg_t['start'];     foreach ($arg_t as $cle=>$val)     {         if($cle!='start')             {             $prcnt_t=round(((round(($val-$prv_val)*1000,4)/$tttime)*100),1);             if ($arg_ra) $ar_aff[$prv_cle.' -> '.$cle]=$prcnt_t;             $aff.=$prv_cle.' -> '.$cle.' : '.$prcnt_t." %\n";             $prv_val=$val;             $prv_cle=$cle;         }     }     if ($arg_ra) return $ar_aff;     return $aff;   } ?>

[#18] singh206 at gmail dot com [2009-04-10 11:35:29]

<?php class StopWatch { public $total; public $time; public function __construct() { $this->total = $this->time = microtime(true); } public function clock() { return -$this->time + ($this->time = microtime(true)); } public function elapsed() { return microtime(true) - $this->total; } public function reset() { $this->total=$this->time=microtime(true); } } $stopwatch = new StopWatch(); usleep(1000000); echo "Checkpoint 1: ".$stopwatch->clock()." seconds<br />"; usleep(1000000); echo "Checkpoint 2: ".$stopwatch->clock()." seconds<br />"; echo "Total Elapsed: ".$stopwatch->elapsed()." seconds<br />"; ?>

[#19] christ dot boris at nospam gmail dot com [2008-09-13 12:39:37]

Hi, I made a function to get the generation page time :

<?php function gentime() { static $a; if($a == 0) $a = microtime(true); else return (string)(microtime(true)-$a); } ?>

(You can add a round() to the return value if you want)

Use :

<?php # you should include your libraries/conf files here (including the gentime function) gentime(); # your source code here echo 'Generated in '.gentime().' seconds.' ?>

[#20] pascalxusPLEASENOSPAM at yahoo dot com [2008-07-12 01:19:12]

I wanted to find out whether echo would be quicker in small chunks or one large chunk to test the theory mentioned in the previous post.  The following experiment shows that there is no significant performance difference, in terms of execution time elapsed, between the two methods of using echo.  I ran two test cases, one with a string that is 100000 bytes long and another with a string length of 1000000.  The source code follows below.

<?php function echobig($string, $bufferSize = 8192) {     $splitString = str_split($string, $bufferSize);     foreach($splitString as $chunk)         echo $chunk; } global $dat; $dat = ""; function testit() { global $dat; $data = ""; for( $a = 0; $a <= 1000000; $a += 1 ) $data .= "a"; $u1= microtime(true); echobig( $data ); $u2= microtime(true); echo $data; $u3= microtime(true); $diff = $u2 - $u1; $diff2= $u3 - $u2; $dat .= "$diff2 $diff    $u2  $u1\r\n"; } $i = 0; while( $i < 5 ) {   testit(); $i += 1; } global $dat; $fp = fopen( "../Data/results.txt", "w" ); fwrite( $fp, $dat ); fclose( $fp ); ?>

You can run the above experiment yourself or you can look at my test data.  I got some test data here:  http://www.codesplunk.com/examples/echo.html

[#21] kpsimoulis [at] genatec [2008-06-05 12:53:19]

This function is very useful for putting a start and end point in your page to find out where is the delay.

<?php $start = microtime(true); // My source code here $end = microtime(true); echo $end."-".$start."=".($end - $start). " seconds"; ?>

If you try this example above (without any source code between the start and the end point). You will get an ugly value, something like:
1212690530.4132-1212690530.4132=8.1062316894531E-6 seconds

You will wonder why you get this because both numbers seem to be equal. Well this is because there is a hidden precision that we are not able to see.

To solve this problem I made a new function:

<?php function my_microtime($precision = 4) { return round(microtime(true),4); } $start = microtime(true); // My source code here $end = microtime(true); echo $end."-".$start."=".substr(($end - $start),0,5). " seconds"; ?>

It would be useful if they add another parameter for precision in this function or at least another boolean that will not include the hidden precision.
You can read more about the hidden precision in http://php.net/float

[#22] Peter Kehl [2008-05-30 03:31:03]

This function allows you to easily calculate time difference between two points in time without losing the precision.

<?php function microtime_diff( $start, $end=NULL ) { if( !$end ) { $end= microtime(); } list($start_usec, $start_sec) = explode(" ", $start); list($end_usec, $end_sec) = explode(" ", $end); $diff_sec= intval($end_sec) - intval($start_sec); $diff_usec= floatval($end_usec) - floatval($start_usec); return floatval( $diff_sec ) + $diff_usec; } ?>

[#23] luke at lucanos dot com [2008-05-28 16:48:08]

Rather than using the list() function, etc. I have found the following code to be a bit cleaner and simpler:
<?php $theTime = array_sum( explode( ' ' , microtime() ) ); echo $theTime; # Displays "1212018372.3366" ?>

[#24] admin at emuxperts dot net [2006-08-20 19:37:40]

This little function comes in handy if you want a single integer when your server doesn't have php >= 5.0

It returns seconds passed unix epoch to the microsecond. Or microseconds since unix epoch.

<?php //A hack for PHP < 5.0 function utime($inms){ $utime = preg_match("/^(.*?) (.*?)$/", microtime(), $match); $utime = $match[2] + $match[1]; if($inms){ $utime *= 1000000; } return $utime; } //Example: print utime(); //Returns: //1156127104.746352 Seconds //Example two: print utime(1); //Returns: //1156127104746352 Microseconds ?>

[#25] EdorFaus [2006-05-16 12:47:51]

Of the methods I've seen here, and thought up myself, to convert microtime() output into a numerical value, the microtime_float() one shown in the documentation proper(using explode,list,float,+) is the slowest in terms of runtime.

I implemented the various methods, ran each in a tight loop 1,000,000 times, and compared runtimes (and output). I did this 10 times to make sure there wasn't a problem of other things putting a load spike on the server. I'll admit I didn't take into account martijn at vanderlee dot com's comments on testing accuracy, but as I figured the looping code etc would be the same, and this was only meant as a relative comparison, it should not be necessary.

The above method took on average 5.7151877 seconds, while a method using substr and simply adding strings with . took on average 3.0144226 seconds. rsalazar at innox dot com dot mx's method using preg_replace used on average 4.1819633 seconds. This shows that there are indeed differences, but for normal use noone is going to notice it.

Note that the substr method mentioned isn't quite the one given anonymously below, but one I made based on it:
<?php $time=microtime(); $timeval=substr($time,11).substr($time,1,9); ?>

Also worth noting is that the microtime_float() method gets faster, and no less accurate, if the (float) conversions are taken out and the variables are simply added together.

Any of the methods that used + or array_sum ended up rounding the result to 2 digits after the decimal point, while (most of) the ones using preg_replace or substr and . kept all the digits.

For accurate timing, since floating-point arithmetic would lose precision, I stored microtime results as-is and calculated time difference with this function:
<?php function microtime_used($before,$after) { return (substr($after,11)-substr($before,11)) +(substr($after,0,9)-substr($before,0,9)); } ?>

For further information, the script itself, etc, see http://edorfaus.xepher.net/div/convert-method-test.php

[#26] radek at pinkbike com [2005-11-24 20:48:14]

A lot of the comments here suggest adding in the following way:  (float)$usec + (float)$sec
Make sure you have the float precision high enough as with the default precision of 12, you are only precise to the 0.01 seconds.
Set this in you php.ini file.
        precision    =  16

[#27] vladson at pc-labs dot info [2005-06-19 03:49:21]

I like to use bcmath for it
<?php function micro_time() { $temp = explode(" ", microtime()); return bcadd($temp[0], $temp[1], 6); } $time_start = micro_time(); sleep(1); $time_stop = micro_time(); $time_overall = bcsub($time_stop, $time_start, 6); echo "Execution time - $time_overall Seconds"; ?>

[#28] php at washboardabs dot net [2005-02-24 00:57:21]

Interesting quirk (tested in PHP 5.0.3): You can get very wacky results from microtime when it is called in the destructor of an object at the end of a script. These times vary enormously and can be in the *past*, when compared to microtime calls in the body of the script.

As a case example, I played with a timer object that measured microtime when it was created at the start of the script, and measured microtime again at the end of the script using __destruct(); and then printed the total execution time (end time - start time) at the bottom of the page. On short scripts, this would often give a negative time!

This quirk does not appear if microtime is measured with an automatic shutdown function (using <?PHP register_shutdown_function('myfunc') ?>. Incidentally, the automatic shutdown functions are called after output buffers are flushed but before object destructors are called.