CODEWITHSUNDEEP
phpmemorymemory-management
erotsppa
erotsppa

Reputation: 15021

How to find memory used by an object in PHP? (sizeof)

How to find memory used by an object in PHP? (c's sizeof). The object I want to find out about is a dictionary with strings and ints in it so it makes it hard to calculate it manually. Also string in php can be of varied length depending on encoding (utf8 etc) correct?

Upvotes: 40

Views: 53942

Answers (6)

Mike Atkinson
Mike Atkinson

Reputation: 1

This method converts the array to a json string and determines the length of that string. The result should be fairly similar to the size of the array (both will have delimiters to partition members of the array or the stringified json) strlen(json_encode(YourArray))

Upvotes: 0

Parvez Alam
Parvez Alam

Reputation: 398

this method could be help you:

function getVariableUsage($var) {
 $total_memory = memory_get_usage();
 $tmp = unserialize(serialize($var));
 return memory_get_usage() - $total_memory; 
}

$var = "Hey, what's you doing?";
echo getVariableUsage($var);

https://www.phpflow.com/

Upvotes: -1

LionsAd
LionsAd

Reputation: 279

If you need to know the size of an already created object or array, you can use the following code to find it out.

<?php

function rec_copy($src) {
  if (is_string($src)) {
    return str_replace('SOME_NEVER_OCCURING_VALUE_145645645734534523', 'XYZ', $src);
  }

  if (is_numeric($src)) {
    return ($src + 0);
  }

  if (is_bool($src)) {
    return ($src?TRUE:FALSE);
  }
  if (is_null($src)) {
    return NULL;
  }

  if (is_object($src)) {
    $new = (object) array();
    foreach ($src as $key => $val) {
      $new->$key = rec_copy($val);
    }
    return $new;
  }

  if (!is_array($src)) {
    print_r(gettype($src) . "\n");
    return $src;
  }

  $new = array();

  foreach ($src as $key => $val) {
    $new[$key] = rec_copy($val);
  }
  return $new;
}

$old = memory_get_usage();
$dummy = rec_copy($src);
$mem = memory_get_usage();

$size = abs($mem - $old);
?>

This essentially creates a copy of the array structure and all of its members.

A not 100% accurate, but still working version is also:

<?php

$old = memory_get_usage();
$dummy = unserialize(serialize($src));
$mem = memory_get_usage();

$size = abs($mem - $old);

Hope that helps for cases where the object is already build.

Upvotes: 10

rekowski
rekowski

Reputation: 169

To get an idea about the objects size, try 

strlen(serialize($object));

It is by no means accurate, but an easy way to get a number for comparison.

Upvotes: 16

zombat
zombat

Reputation: 94147

You could use memory_get_usage().

Run it once before creating your object, then again after creating your object, and take the difference between the two results.

Upvotes: 55

Peter
Peter

Reputation: 421

I don't know that there is a simple way to get the size of an object in PHP. You might just have to do an algorith that

  1. Counts the ints
  2. Multiplies number of ints by size of an int on hard disk
  3. Convert characters in strings to ASCII and
  4. Multiply the ASCII values by how much they take up on disk

I'm sure there is a better way, but this would work, even though it would be a pain.

Upvotes: -6

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