From：
BrokerController start()
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
BrokerController.this.registerBrokerAll(true, false, brokerConfig.isForceRegister());
} catch (Throwable e) {
log.error("registerBrokerAll Exception", e);
}
}
}, 1000 * 10, Math.max(10000, Math.min(brokerConfig.getRegisterNameServerPeriod(), 60000)), TimeUnit.MILLISECONDS);
Math.max(10000, Math.min(brokerConfig.getRegisterNameServerPeriod(), 60000))
上面这一句直接控制了中间的自定义值的范围，避免了大量的if判断
