memory_get_usage

(PHP 4 >= 4.3.2, PHP 5, PHP 7)

memory_get_usage — 返回分配给 PHP 的内存量

说明

int memory_get_usage ([ bool $real_usage = false ] )

返回当前分配给你的 PHP 脚本的内存量，单位是字节（byte）。

参数

real_usage

如果设置为 TRUE，获取系统分配总的内存尺寸，包括未使用的页。如果未设置或者设置为 FALSE，仅仅报告实际使用的内存量。

Note:

PHP 不跟踪非emalloc() 分配的内存

返回值

返回内存量字节数。

更新日志

版本 说明
5.2.1 不需要在编译时使用 --enable-memory-limit 选项就能够使用这个函数。
5.2.0 增加了参数 real_usage。

范例

Example #1 一个 memory_get_usage() 例子

<?php
//这只是个例子，下面的数字取决于你的系统

echo memory_get_usage() . "\n"; // 36640

$a = str_repeat("Hello", 4242);

echo memory_get_usage() . "\n"; // 57960

unset($a);

echo memory_get_usage() . "\n"; // 36744

?>

参见

User Contributed Notes

stanislav dot eckert at vizson dot de 19-Feb-2017 12:08
memory_get_usage() is used to retrieve the memory allocated to PHP only (or your running script). But intuitively, many people expect to get the memory usage of the system, based on the name of the function.

So if you need the overall memory usage, following function might be helpful. If retrieves the memory usage either in percent (without the percent sign) or in bytes by returning an array with free and overall memory of your system. Tested with Windows (7) and Linux (on an Raspberry Pi 2):

<?php

    // Returns used memory (either in percent (without percent sign) or free and overall in bytes)
    function getServerMemoryUsage($getPercentage=true)
    {
        $memoryTotal = null;
        $memoryFree = null;

        if (stristr(PHP_OS, "win")) {
            // Get total physical memory (this is in bytes)
            $cmd = "wmic ComputerSystem get TotalPhysicalMemory";
            @exec($cmd, $outputTotalPhysicalMemory);

            // Get free physical memory (this is in kibibytes!)
            $cmd = "wmic OS get FreePhysicalMemory";
            @exec($cmd, $outputFreePhysicalMemory);

            if ($outputTotalPhysicalMemory && $outputFreePhysicalMemory) {
                // Find total value
                foreach ($outputTotalPhysicalMemory as $line) {
                    if ($line && preg_match("/^[0-9]+\$/", $line)) {
                        $memoryTotal = $line;
                        break;
                    }
                }

                // Find free value
                foreach ($outputFreePhysicalMemory as $line) {
                    if ($line && preg_match("/^[0-9]+\$/", $line)) {
                        $memoryFree = $line;
                        $memoryFree *= 1024;  // convert from kibibytes to bytes
                        break;
                    }
                }
            }
        }
        else
        {
            if (is_readable("/proc/meminfo"))
            {
                $stats = @file_get_contents("/proc/meminfo");

                if ($stats !== false) {
                    // Separate lines
                    $stats = str_replace(array("\r\n", "\n\r", "\r"), "\n", $stats);
                    $stats = explode("\n", $stats);

                    // Separate values and find correct lines for total and free mem
                    foreach ($stats as $statLine) {
                        $statLineData = explode(":", trim($statLine));

                        //
                        // Extract size (TODO: It seems that (at least) the two values for total and free memory have the unit "kB" always. Is this correct?
                        //

                        // Total memory
                        if (count($statLineData) == 2 && trim($statLineData[0]) == "MemTotal") {
                            $memoryTotal = trim($statLineData[1]);
                            $memoryTotal = explode(" ", $memoryTotal);
                            $memoryTotal = $memoryTotal[0];
                            $memoryTotal *= 1024;  // convert from kibibytes to bytes
                        }

                        // Free memory
                        if (count($statLineData) == 2 && trim($statLineData[0]) == "MemFree") {
                            $memoryFree = trim($statLineData[1]);
                            $memoryFree = explode(" ", $memoryFree);
                            $memoryFree = $memoryFree[0];
                            $memoryFree *= 1024;  // convert from kibibytes to bytes
                        }
                    }
                }
            }
        }

        if (is_null($memoryTotal) || is_null($memoryFree)) {
            return null;
        } else {
            if ($getPercentage) {
                return (100 - ($memoryFree * 100 / $memoryTotal));
            } else {
                return array(
                    "total" => $memoryTotal,
                    "free" => $memoryFree,
                );
            }
        }
    }

    function getNiceFileSize($bytes, $binaryPrefix=true) {
        if ($binaryPrefix) {
            $unit=array('B','KiB','MiB','GiB','TiB','PiB');
            if ($bytes==0) return '0 ' . $unit[0];
            return @round($bytes/pow(1024,($i=floor(log($bytes,1024)))),2) .' '. (isset($unit[$i]) ? $unit[$i] : 'B');
        } else {
            $unit=array('B','KB','MB','GB','TB','PB');
            if ($bytes==0) return '0 ' . $unit[0];
            return @round($bytes/pow(1000,($i=floor(log($bytes,1000)))),2) .' '. (isset($unit[$i]) ? $unit[$i] : 'B');
        }
    }

    // Memory usage: 4.55 GiB / 23.91 GiB (19.013557664178%)
    $memUsage = getServerMemoryUsage(false);
    echo sprintf("Memory usage: %s / %s (%s%%)",
        getNiceFileSize($memUsage["total"] - $memUsage["free"]),
        getNiceFileSize($memUsage["total"]),
        getServerMemoryUsage(true)
    );

?>

The function getNiceFileSize() is not required. Just used to shorten size in bytes.

Note: If you need the server load (CPU usage), I wrote a nice function to get that too: http://php.net/manual/en/function.sys-getloadavg.php#118673
miami at blackcrystal dot net 11-Mar-2015 08:46
Sometimes, we need all memory to run our task, we do ini_set('memory_limit',  -1 ), or maximum value we have.

To avoid stuck of server on long and memory consuming tasks, i wrote this check. This is not the same as memory_get_usage() do, but more. It shows virtual memory amount, taken by your process. In percents.

<?php
    function getVirtualMemoryTaken()
    {
        $pid = getmypid();
        $a = `ps -p $pid v | awk 'END{print $9}'`;
        return $a*1;
    }
?>

It works only in linux, tested in Ubuntu 14.

<?php
    $a = ' ';
    do {  $a .= $a . $a; }
    while (getVirtualMemoryTaken() < 20 );
?>
Alex Aulbach 22-Mar-2011 10:14
Note, that the official IEC-prefix for kilobyte, megabyte and so on are KiB, MiB, TiB and so on.

See http://en.wikipedia.org/wiki/Tebibyte

At first glance this may sound like "What the hell? Everybody knows, that we mean 1024 not 1000 and the difference is not too big, so what?". But in about 10 years, the size of harddisks (and files on them) reaches the petabyte-limit and then the difference between PB and PiB is magnificent.

Better to get used to it now. :)
lorin dot weilenmann at gmail dot com 26-Nov-2010 10:37
I can confirm that this function triggers a garbage collection. I have a script that exceeded 128MB of memory at some point and ended with a fatal error. I was confused, because the script dealt with some large files initially, but the memory load from that point on should have been marginal, and the error occurred at the very end.

Those large files were dealt in a dedicated function and i even used unset() on the variable holding the file after the file was written to disk inside that function. So the memory should have been cleared twice, first after the unset() call, and second once the function ended.

To debug the memory usage, I called memory_get_usage(true) at some points and echo-ed the memory allocation. Just by adding a few echos here and there in the script, the memory usage never exceeded 1MB overhead (on top of the current file size) and the memory error disappeared.
xelozz -at- gmail.com 18-Feb-2010 11:34
To get the memory usage in KB or MB

<?php
function convert($size)
 {
    $unit=array('b','kb','mb','gb','tb','pb');
    return @round($size/pow(1024,($i=floor(log($size,1024)))),2).' '.$unit[$i];
 }

echo convert(memory_get_usage(true)); // 123 kb
?>
mario 16-Nov-2009 06:11
not sure how this works internally but I have observed sort of side effects here: calling this function apparently triggers PHP's "garbage collector" -- and frees some memory. I managed to "fix" some savagely coded mess of a web application solely by calling this function just before the code that would usually throw out-of-memory errors. the php version there was 5.2.10
jeff dot peck at snet dot net 19-Aug-2009 06:22
To get the memory usage in KB or MB

<?php
    function echo_memory_usage() {
        $mem_usage = memory_get_usage(true);
       
        if ($mem_usage < 1024)
            echo $mem_usage." bytes";
        elseif ($mem_usage < 1048576)
            echo round($mem_usage/1024,2)." kilobytes";
        else
            echo round($mem_usage/1048576,2)." megabytes";
           
        echo "<br/>";
    }
?>
miteigi nemoto (miteigi at yandex dot ru) 19-Nov-2008 05:19
Decision a memory_get_usage problem for windows system

Tested OS: Windows XP
Server: Apache

PHP must be loaded as CGI to get correctly memory usage by Process ID ( getmypid() ) and with cmd-tools like tasklist.exe

PHP as CGI have your own PID instead constant Apache PID and you get a true memory size independed form Apache memory usage.

Configure in httpd.conf of Apache:

1. Comment the line like this:
LoadModule php4_module "/usr/local/php/sapi/php4apache.dll"
or
LoadModule php5_module "/usr/local/php5/php5apache.dll"

2. Add this and edit your path to php:
<Directory "z:/usr/local/php">
  Options ExecCGI
</Directory>
ScriptAlias "/__php_dir__/" "z:/usr/local/php/"
Action application/x-httpd-php "/__php_dir__/php.exe"

3. Restart Apache

Use this PHP-code:

<?php
/**
* A memory_get_usage() for Windows System, wich compiled without --enable-memory-limit
* PHP must be loaded as CGI
* Greetings form miteigi nemoto
* @return string
*/
function memory_get_usage_by_tasklist()
{
    $output = array();
    exec( 'tasklist ', $output );
    foreach ($output as $value)
    {
        $ex=explode(" ",$value);
        $count_ex=count($ex);
        if (eregi(" ".getmypid()." Console",$value))
        {
            $memory_size=$ex[$count_ex-2]." Kb";
            return $memory_size;
        }
    }
}
echo memory_get_usage_by_tasklist();
?>
joe at schmoe dot com 23-Dec-2006 09:44
the various memory_get_usage replacements here don't seem to work on Mac OS X 10.4(Intel)

I got it to work like this...

<?php
function memory_get_usage()
{
     $pid = getmypid();
     exec("ps -o rss -p $pid", $output);
     return $output[1] *1024;
}
?>
e dot a dot schultz at gmail dot com 09-Apr-2006 01:41
This is a function that should work for both Windows XP/2003 and most distrabutions of UNIX and Mac OS X.

<?php
if( !function_exists('memory_get_usage') )
{
    function memory_get_usage()
    {
        //If its Windows
        //Tested on Win XP Pro SP2. Should work on Win 2003 Server too
        //Doesn't work for 2000
        //If you need it to work for 2000 look at http://us2.php.net/manual/en/function.memory-get-usage.php#54642
        if ( substr(PHP_OS,0,3) == 'WIN')
        {
               if ( substr( PHP_OS, 0, 3 ) == 'WIN' )
                {
                    $output = array();
                    exec( 'tasklist /FI "PID eq ' . getmypid() . '" /FO LIST', $output );
       
                    return preg_replace( '/[\D]/', '', $output[5] ) * 1024;
                }
        }else
        {
            //We now assume the OS is UNIX
            //Tested on Mac OS X 10.4.6 and Linux Red Hat Enterprise 4
            //This should work on most UNIX systems
            $pid = getmypid();
            exec("ps -eo%mem,rss,pid | grep $pid", $output);
            $output = explode("  ", $output[0]);
            //rss is given in 1024 byte units
            return $output[1] * 1024;
        }
    }
}
?>
grey - greywyvern - com 17-Aug-2005 09:37
If nothing else in the user notes below works for you, you can get a very (VERY) rough estimate of PHP memory usage by outputting the $GLOBALS array, stripping it of indentation whitespace, and counting the characters in the resulting string.  This method has a very high overhead (to be expected), but works on all operating systems, regardless of whether or not they have the --enable-memory-limit config option set.  I find that the syntax overhead of the print_r() statement roughly accounts for the PHP runtime base memory usage.

The code below is set up to work on all arrays, not just the $GLOBALS array.  Keep in mind that outside data referenced by resource IDs, such as database results and open file data, is not included in this total.

<?php

function array_size($arr) {
  ob_start();
  print_r($arr);
  $mem = ob_get_contents();
  ob_end_clean();
  $mem = preg_replace("/\n +/", "", $mem);
  $mem = strlen($mem);
  return $mem;
}

$memEstimate = array_size($GLOBALS);

?>

Use only if being off to either side by at least 20% is acceptible for your purposes.
vesa dot kivisto at nepton dot fi 14-Jul-2005 03:02
[EDIT by danbrown AT php DOT net: This function will only extend Windows versions of PHP where the server has the required third-party software.]

I was unable to get the previous examples working properly and created code which works at least for me. Enjoy!

<?php
// Please note that you'll need the pslist.exe utility from http://www.sysinternals.com/Utilities/PsTools.html
// This is because win/2000 itself does not provide a task list utility.
//
function getMemoryUsage() {

 // try to use PHP build in function
 if( function_exists('memory_get_usage') ) {
  return memory_get_usage();
 }

 // Try to get Windows memory usage via pslist command
 if ( substr(PHP_OS,0,3) == 'WIN') {
 
  $resultRow = 8;
  $resultRowItemStartPosition = 34;
  $resultRowItemLength = 8;
 
  $output = array();
  exec('pslist -m ' . getmypid() , $output);
   
  return trim(substr($output[$resultRow], $resultRowItemStartPosition, $resultRowItemLength)) . ' KB';
 
 }

 
 // No memory functionality available at all
 return '<b style="color: red;">no value</b>';
 
}
?>
guenter_doege at web dot de 11-Jul-2005 08:28
The Win XP / 2003 workaround script will also work with windows 2000 with a few slight modifications.

Please note that you'll need the pslist.exe utility from http://www.sysinternals.com/Utilities/PsTools.html because win/2000 itself does not provide a task list utility.

<?php

function getMemUsage()
{
    
       if (function_exists('memory_get_usage'))
       {
           return memory_get_usage();
       }
       else if ( substr(PHP_OS,0,3) == 'WIN')
       {
           // Windows 2000 workaround

           $output = array();
           exec('pslist ' . getmypid() , $output);
           return trim(substr($output[8],38,10));
       }
       else
       {
           return '<b style="color: red;">no value</b>';
       }
}
?>
MagicalTux at FF dot st 25-May-2005 09:08
When you need to get the OS, do not use $_SERVER['OS'] or $_ENV['OS'], better use PHP_OS constant !
<?php
if (substr(PHP_OS,0,3)=='WIN') {
  // [...]
}
?>

You also have other values such as CYGWIN_NT-5.0, Linux, ... this is the best way to get system's os (anyone on linux can do an "export OS=windows")
randolphothegreat at yahoo dot com 29-Nov-2004 10:37
[EDIT by danbrown AT php DOT net: This is intended by the author to only be used with PHP 4 < 4.3.2.]

I'd just like to point out that although sandeepc at myrealbox dot com's idea for displaying the current memory usage is a good one, it's perhaps a bad idea to pipe the entire process list through grep. A better performing method would be to select only the process we're interested in:

<?php
$pid = getmypid();
error_log('MEMORY USAGE (% KB PID ): ' . `ps --pid $pid --no-headers -o%mem,rss,pid`);
?>

True, it's not much of a performance boost, but every bit helps.
ad-rotator.com 14-May-2004 07:31
The method sandeepc at myrealbox dot com posted yields larger memory usage, my guess is that it includes all the PHP interpreter/internal code and not just the script being run.

1) Use ps command
MEMORY USAGE (% KB PID ):  0.8 12588 25087 -> about 12MB
2) Use memory_get_usage()
int(6041952) -> about 6MB