PHP: Measure size in kilobytes of a object/array?

Question

What's an appropriate way of measure a PHP objects actual size in bytes/kilobytes?

Reason for asking:
I am utilizing memcached for cache storage in my web application that will be used by non-technical customers. However, since memcached has a maximum size of 1mb , it would be great to have a function set up from the beginning that I can be used to measure size of selected objects/arrays/datasets, to prevent them from growing to big.

Note that I am only planning on using this as a alert/diagnostic tool to keep track of the cache performance and storage possibilities over time. I assume that calculating speed on each memcached set/add call would slow down things a bit.

I am also aware of storing big datasets in memcached takes away the whole idea of storing things in the RAM, and that is exactly why I need to know in beforehand to prevent customers building up to big datasets.

Thanks a lot

See below the official manual page. php.net/manual/en/memcache.set.php And you will find "Parameters > var" section. > The variable to store. Strings and integers are stored as is, other > types are stored serialized. — Oh Seok-Geun
– Oh Seok-Geun, Commented Jul 24, 2018 at 2:47

GitaarLAB · Accepted Answer · 2013-07-12 14:21:57Z

33

Well, since Memcached doesn't store raw objects (it actually stores the serialiezd version), you can do this:

$serializedFoo = serialize($foo);
if (function_exists('mb_strlen')) {
    $size = mb_strlen($serializedFoo, '8bit');
} else {
    $size = strlen($serializedFoo);
}

edited Jul 12, 2013 at 14:21

GitaarLAB

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answered Jun 18, 2010 at 19:16

ircmaxell

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4 Comments

Industrial Over a year ago

Hi! That's just what I was about to ask. How does it handle UTF8 and multiple byte characters?

ircmaxell Over a year ago

Well, it all depends. If you have mb_string function overloading on, then you have issues. If not, strlen will return the byte length (which is what you want in the first place). If you have mbstring.func_overload on, you can use mb_strlen(serialize($foo), '8bit'); in place of strlen. But note, mb_string must be installed to use it. I'll edit in a more robust version...

Industrial Over a year ago

Thanks a lot for your help ircmaxell! Great stuff

Jan Święcki Over a year ago

@ircmaxell on line 5 of the script you have one too many paranthesis. (can't edit, because SO says edit must have at least 6 characters).

fdrv · Accepted Answer · 2016-03-16 21:35:43Z

-2

Another easy way pute content of array to file and then check file size.

$str = print_r($array, true);
file_put_contents('data.txt', $str);
$size = filesize('data.txt');

edited Mar 16, 2016 at 21:35

answered Aug 13, 2014 at 17:47

fdrv

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3 Comments

Andrei Surdu Over a year ago

What? Never do that!

f4der Over a year ago

It would be a challenge to find a method that is more inefficient than this one..

Tomer Gal Over a year ago

Don't you dare doing this

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