public static function start() { if (!self::isOpen()) { return false; } if (self::$is_start === true) { return false; } //XHPROF_FLAGS_NO_BUILTINS 是否跳过内部函数 function_exists('xhprof_enable') && xhprof_enable(XHPROF_FLAGS_CPU | XHPROF_FLAGS_MEMORY); self::$is_start = true; }