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run code in 300+ PHP versions simultaneously
<?php class FOO { public $f; } class BAR { public $f; } for ($i = 0; $i < 100; $i++) { $a = new FOO(); $b = new BAR(); $a->f = $b; $b->f = $a; print "Memory usage: " . number_format(memory_get_usage(true)) . " bytes\n"; unset($a); unset($b); }

preferences:
34.83 ms | 402 KiB | 5 Q