If performance is you absolute driving characteristic, then by all means use the fastest one. Just make sure you have a full understanding of the differences before you make a choice
- JSON converts UTF-8 characters to unicode escape sequences.
serialize()does not. - JSON will have no memory of what the object’s original class was (they are always restored as instances of stdClass).
- You can’t leverage
__sleep()and__wakeup()with JSON - Only public properties are serialized with JSON
- JSON is more portable
And there’s probably a few other differences I can’t think of at the moment.
A simple speed test to compare the two
<?php
ini_set( 'display_errors', 1 );
error_reporting( E_ALL );
// Make a bit, honkin test array
// You may need to adjust this depth to avoid memory limit errors
$testArray = fillArray( 0, 5 );
// Time json encoding
$start = microtime( true );
json_encode( $testArray );
$jsonTime = microtime( true ) - $start;
echo "JSON encoded in $jsonTime seconds<br>";
// Time serialization
$start = microtime( true );
serialize( $testArray );
$serializeTime = microtime( true ) - $start;
echo "PHP serialized in $serializeTime seconds<br>";
// Compare them
if ( $jsonTime < $serializeTime )
{
echo "json_encode() was roughly " . number_format( ($serializeTime / $jsonTime - 1 ) * 100, 2 ) . "% faster than serialize()";
}
else if ( $serializeTime < $jsonTime )
{
echo "serialize() was roughly " . number_format( ($jsonTime / $serializeTime - 1 ) * 100, 2 ) . "% faster than json_encode()";
} else {
echo 'Unpossible!';
}
function fillArray( $depth, $max )
{
static $seed;
if ( is_null( $seed ) )
{
$seed = array( 'a', 2, 'c', 4, 'e', 6, 'g', 8, 'i', 10 );
}
if ( $depth < $max )
{
$node = array();
foreach ( $seed as $key )
{
$node[$key] = fillArray( $depth + 1, $max );
}
return $node;
}
return 'empty';
}Results
JSON encoded in 0.057723045349121 seconds
PHP serialized in 0.064256906509399 seconds
json_encode() was roughly 11.32% faster than serialize()