RocketMQ broker busy, start flow control for a while原因

[2pc]

直接全局搜源码，是BrokerFastFailure里边启动的线程BrokerFastFailureScheduledThread执行的

public class BrokerFastFailure {
    private static final InternalLogger log = InternalLoggerFactory.getLogger(LoggerName.BROKER_LOGGER_NAME);
    private final ScheduledExecutorService scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(new ThreadFactoryImpl(
        "BrokerFastFailureScheduledThread"));
//省略部分代码
    public void start() {
        this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
            @Override
            public void run() {
                if (brokerController.getBrokerConfig().isBrokerFastFailureEnable()) {
                    cleanExpiredRequest();
                }
            }
        }, 1000, 10, TimeUnit.MILLISECONDS);//每隔10ms执行一次
    }

如果isOSPageCacheBusy就会设置RequestTask的returnResponse为SYSTEM_BUSY，也就是broker busy, start flow control

    private void cleanExpiredRequest() {
        while (this.brokerController.getMessageStore().isOSPageCacheBusy()) {
            try {
                if (!this.brokerController.getSendThreadPoolQueue().isEmpty()) {
                    final Runnable runnable = this.brokerController.getSendThreadPoolQueue().poll(0, TimeUnit.SECONDS);
                    if (null == runnable) {
                        break;
                    }

                    final RequestTask rt = castRunnable(runnable);
                    rt.returnResponse(RemotingSysResponseCode.SYSTEM_BUSY, String.format("[PCBUSY_CLEAN_QUEUE]broker busy, start flow control for a while, period in queue: %sms, size of queue: %d", System.currentTimeMillis() - rt.getCreateTimestamp(), this.brokerController.getSendThreadPoolQueue().size()));
                } else {
                    break;
                }
            } catch (Throwable ignored) {
            }
        }

        cleanExpiredRequestInQueue(this.brokerController.getSendThreadPoolQueue(),//queue大小10000
            this.brokerController.getBrokerConfig().getWaitTimeMillsInSendQueue());//200ms

        cleanExpiredRequestInQueue(this.brokerController.getPullThreadPoolQueue(),//queue大小100000
            this.brokerController.getBrokerConfig().getWaitTimeMillsInPullQueue());//5*1000

        cleanExpiredRequestInQueue(this.brokerController.getHeartbeatThreadPoolQueue(),//queue大小50000
            this.brokerController.getBrokerConfig().getWaitTimeMillsInHeartbeatQueue());//31 * 1000

        cleanExpiredRequestInQueue(this.brokerController.getEndTransactionThreadPoolQueue(), this//queue大小500000
            .brokerController.getBrokerConfig().getWaitTimeMillsInTransactionQueue());//3 * 1000
    }

cleanExpiredRequestInQueue每个200ms就会将其从SendThreadPoolQueue移除,其他Queue以及waitTime如上
RequestTask 设置stopRun状态为true,同时设置returnResponse为SYSTEM_BUSY，也就是broker busy, start flow control

    void cleanExpiredRequestInQueue(final BlockingQueue<Runnable> blockingQueue, final long maxWaitTimeMillsInQueue) {
        while (true) {
            try {
                if (!blockingQueue.isEmpty()) {
                    final Runnable runnable = blockingQueue.peek();
                    if (null == runnable) {
                        break;
                    }
                    final RequestTask rt = castRunnable(runnable);
                    if (rt == null || rt.isStopRun()) {
                        break;
                    }

                    final long behind = System.currentTimeMillis() - rt.getCreateTimestamp();
                    if (behind >= maxWaitTimeMillsInQueue) {
                        if (blockingQueue.remove(runnable)) {
                            rt.setStopRun(true);
                            rt.returnResponse(RemotingSysResponseCode.SYSTEM_BUSY, String.format("[TIMEOUT_CLEAN_QUEUE]broker busy, start flow control for a while, period in queue: %sms, size of queue: %d", behind, blockingQueue.size()));
                        }
                    } else {
                        break;
                    }
                } else {
                    break;
                }
            } catch (Throwable ignored) {
            }
        }
    }

isOSPageCacheBusy,只要当前时间与上一条消息存储时的开始时间大于1000ms，小于10000ms

  public boolean isOSPageCacheBusy() {
      long begin = this.getCommitLog().getBeginTimeInLock();
      long diff = this.systemClock.now() - begin;

      return diff < 10000000
          && diff > this.messageStoreConfig.getOsPageCacheBusyTimeOutMills();//1000ms
  }

另外返回SYSTEM_BUSY，客户端不会重试