system call select exceeded the maximum number of connections 256.

            $count = $flag === self::EV_READ ? \count($this->_readFds) : \count($this->_writeFds);
            if ($count >= 1024) {
                echo "Warning: system call select exceeded the maximum number of connections 1024, please install event/libevent extension for more connections.\n";
            } else if (\DIRECTORY_SEPARATOR !== '/' && $count >= 256) {
                echo "Warning: system call select exceeded the maximum number of connections 256.\n";
            }