serialize a large array in PHP?

Question

I am curious, is there a size limit on serialize in PHP. Would it be possible to serialize an array with 5,000 keys and values so it can be stored into a cache?

I am

Answer 1

Ok... more numbers! (PHP 5.3.0 OSX, no opcode cache)

@Pascal's code on my machine for n=1 at 10k iters produces:

float(18.884856939316)
int(1075900)

I add unserialize() to the above as so.

$num = 1;

$list = array_fill(0, 5000, str_repeat('1234567890', $num));

$before = microtime(true);
for ($i=0 ; $i<10000 ; $i++) {
    $str = serialize($list);
    $list = unserialize($str);
}
$after = microtime(true);

var_dump($after-$before);
var_dump(memory_get_peak_usage());

produces

float(50.204112052917)
int(1606768) 

I assume the extra 600k or so are the serialized string.

I was curious about var_export and its include/eval partner $str = var_export($list, true); instead of serialize() in the original produces

float(57.064643859863)
int(1066440)

so just a little less memory (at least for this simple example) but way more time already.

adding in eval('$list = '.$str.';'); instead of unserialize in the above produces

float(126.62566018105)
int(2944144)

Indicating theres probably a memory leak somewhere when doing eval :-/.

So again, these aren't great benchmarks (I really should isolate the eval/unserialize by putting the string in a local var or something, but I'm being lazy) but they show the associated trends. var_export seems slow.