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<?php class Example { public $foo = "bar"; } $e = new Example(); var_dump(memory_get_usage(true)); // increase memory $e->foo = str_repeat($e->foo, 10000000); var_dump(memory_get_usage(true)); // no significant increase in memory because of copy-on-write $x = get_object_vars($e); var_dump(memory_get_usage(true)); // write happens, so a copy is made, so memory increases $x["foo"] = $x["foo"] . ""; var_dump(memory_get_usage(true));
Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.25, 7.2.0 - 7.2.13, 7.3.0
int(2097152) int(32100352) int(32100352) int(62103552)
Output for 5.6.38
int(262144) int(30408704) int(30408704) int(60555264)

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