之前分析了PullConsumer的整个流程，这次来看看PushConsumer的启动流程，老样子我们来看DefaultMQPushConsumer的构造
public DefaultMQPushConsumer(final String consumerGroup, RPCHook rpcHook,
AllocateMessageQueueStrategy allocateMessageQueueStrategy) {
this.consumerGroup = consumerGroup;
this.allocateMessageQueueStrategy = allocateMessageQueueStrategy;
defaultMQPushConsumerImpl = new DefaultMQPushConsumerImpl(this, rpcHook);
}很清晰，三个参数分别是消费者组名，rpc钩子函数，分配消息队列策略(默认是平均分配)。
DefaultMQPushConsumer的start方法调用了DefaultMQPushConsumerImpl的start()方法，来看DefaultMQPushConsumerImpl的start()方法
public synchronized void start() throws MQClientException {
switch (this.serviceState) {
case CREATE_JUST:
log.info("the consumer [{}] start beginning. messageModel={}, isUnitMode={}", this.defaultMQPushConsumer
.getConsumerGroup(), this.defaultMQPushConsumer.getMessageModel(), this.defaultMQPushConsumer.isUnitMode());
this.serviceState = ServiceState.START_FAILED;
this.checkConfig();
this.copySubscription();
if (this.defaultMQPushConsumer.getMessageModel() == MessageModel.CLUSTERING) {
this.defaultMQPushConsumer.changeInstanceNameToPID();
}
this.mQClientFactory = MQClientManager.getInstance().getAndCreateMQClientInstance(this.defaultMQPushConsumer
, this.rpcHook);
this.rebalanceImpl.setConsumerGroup(this.defaultMQPushConsumer.getConsumerGroup());
this.rebalanceImpl.setMessageModel(this.defaultMQPushConsumer.getMessageModel());
this.rebalanceImpl.setAllocateMessageQueueStrategy(this.defaultMQPushConsumer.getAllocateMessageQueueStrategy());
this.rebalanceImpl.setmQClientFactory(this.mQClientFactory);
this.pullAPIWrapper = new PullAPIWrapper(
mQClientFactory,
this.defaultMQPushConsumer.getConsumerGroup(), isUnitMode());
this.pullAPIWrapper.registerFilterMessageHook(filterMessageHookList);
if (this.defaultMQPushConsumer.getOffsetStore() != null) {
this.offsetStore = this.defaultMQPushConsumer.getOffsetStore();
} else {
switch (this.defaultMQPushConsumer.getMessageModel()) {
case BROADCASTING:
this.offsetStore = new LocalFileOffsetStore(this.mQClientFactory, this.defaultMQPushConsumer
.getConsumerGroup());
break;
case CLUSTERING:
this.offsetStore = new RemoteBrokerOffsetStore(this.mQClientFactory, this.defaultMQPushConsumer
.getConsumerGroup());
break;
default:
break;
}
this.defaultMQPushConsumer.setOffsetStore(this.offsetStore);
}
this.offsetStore.load();
if (this.getMessageListenerInner() instanceof MessageListenerOrderly) {
this.consumeOrderly = true;
this.consumeMessageService =
new ConsumeMessageOrderlyService(this, (MessageListenerOrderly) this.getMessageListenerInner());
} else if (this.getMessageListenerInner() instanceof MessageListenerConcurrently) {
this.consumeOrderly = false;
this.consumeMessageService =
new ConsumeMessageConcurrentlyService(this, (MessageListenerConcurrently) this.getMessageListenerInner());
}
this.consumeMessageService.start();
boolean registerOK = mQClientFactory.registerConsumer(this.defaultMQPushConsumer.getConsumerGroup(), this);
if (!registerOK) {
this.serviceState = ServiceState.CREATE_JUST;
this.consumeMessageService.shutdown();
throw new MQClientException("The consumer group[" + this.defaultMQPushConsumer.getConsumerGroup()
+ "] has been created before, specify another name please."
+ FAQUrl.suggestTodo(FAQUrl.GROUP_NAME_DUPLICATE_URL), null);
}
mQClientFactory.start();
log.info("the consumer [{}] start OK.", this.defaultMQPushConsumer.getConsumerGroup());
this.serviceState = ServiceState.RUNNING;
break;
case RUNNING:
case START_FAILED:
case SHUTDOWN_ALREADY:
throw new MQClientException("The PushConsumer service state not OK, maybe started once, "
+ this.serviceState
+ FAQUrl.suggestTodo(FAQUrl.CLIENT_SERVICE_NOT_OK),
null);
default:
break;
}
this.updateTopicSubscribeInfoWhenSubscriptionChanged();
this.mQClientFactory.checkClientInBroker();
this.mQClientFactory.sendHeartbeatToAllBrokerWithLock();
this.mQClientFactory.rebalanceImmediately();
}整个方法是加锁的，跟PullConsumer的一样，先调用checkConfig()，确认consumer的配置是否合法，比如消费者组名，消息模式，是否顺序消费，消息队列分配策略等。然后调用copySubscription()方法，将DefaultPushConsumer的订阅信息构造成SubscriptionData复制到DefaultPushConsumerImpl的subscriptionInner中。然后是消费者客户端MQClientInstance实例的获取过程。接下来配置reblanceImpl、构造pullAPIWrapper实例并给其注册FilterMessageHook。
然后根据消费者的消息模式，选择不同的方式存储消费进度，广播则本地文件，集群则存于远程broker服务器中。我们看下本地文件的方式即LocalFileOffsetStore的方式。
private ConcurrentMap<MessageQueue, AtomicLong> offsetTable =
new ConcurrentHashMap<MessageQueue, AtomicLong>();
@Override
public void load() throws MQClientException {
OffsetSerializeWrapper offsetSerializeWrapper = this.readLocalOffset();
if (offsetSerializeWrapper != null && offsetSerializeWrapper.getOffsetTable() != null) {
offsetTable.putAll(offsetSerializeWrapper.getOffsetTable());
for (MessageQueue mq : offsetSerializeWrapper.getOffsetTable().keySet()) {
AtomicLong offset = offsetSerializeWrapper.getOffsetTable().get(mq);
log.info("load consumer's offset, {} {} {}",
this.groupName,
mq,
offset.get());
}
}
}
private OffsetSerializeWrapper readLocalOffset() throws MQClientException {
String content = null;
try {
content = MixAll.file2String(this.storePath);
} catch (IOException e) {
log.warn("Load local offset store file exception", e);
}
if (null == content || content.length() == 0) {
return this.readLocalOffsetBak();
} else {
OffsetSerializeWrapper offsetSerializeWrapper = null;
try {
offsetSerializeWrapper =
OffsetSerializeWrapper.fromJson(content, OffsetSerializeWrapper.class);
} catch (Exception e) {
log.warn("readLocalOffset Exception, and try to correct", e);
return this.readLocalOffsetBak();
}
return offsetSerializeWrapper;
}
}可以看到读取本地文件的数据(json格式)，反序列化转成offsetSerializeWrapper。
当然我们分析过pull客户端的时候知道，后面消费者客户端会起一个定时任务，定时将内存中的消费进度持久化到本地文件中。
之后根据其messageListenerInner是否属于MessageListenerOrderly，即是否配置了顺序消费。如果选择了顺序消费，那么consumeMessageService成员赋值为ConsumeMessageOrderlyService类的实例，否则为ConsumeMessageConcurrentlyService的实例。然后调用了consumeMessageService的start()方法。我们可以看到非顺序的start()方法仅仅启动了定时清理过期消息的任务。重点来看下顺序消费，即ConsumeMessageOrderlyService的start方法。
public void start() {
if (MessageModel.CLUSTERING.equals(ConsumeMessageOrderlyService.this.defaultMQPushConsumerImpl.messageModel())) {
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
ConsumeMessageOrderlyService.this.lockMQPeriodically();
}
}, 1000 * 1, ProcessQueue.REBALANCE_LOCK_INTERVAL, TimeUnit.MILLISECONDS);
}
} public synchronized void lockMQPeriodically() {
if (!this.stopped) {
this.defaultMQPushConsumerImpl.getRebalanceImpl().lockAll();
}
} public void lockAll() {
HashMap<String, Set<MessageQueue>> brokerMqs = this.buildProcessQueueTableByBrokerName();
Iterator<Entry<String, Set<MessageQueue>>> it = brokerMqs.entrySet().iterator();
while (it.hasNext()) {
Entry<String, Set<MessageQueue>> entry = it.next();
final String brokerName = entry.getKey();
final Set<MessageQueue> mqs = entry.getValue();
if (mqs.isEmpty())
continue;
FindBrokerResult findBrokerResult = this.mQClientFactory.findBrokerAddressInSubscribe(brokerName, MixAll.MASTER_ID, true);
if (findBrokerResult != null) {
LockBatchRequestBody requestBody = new LockBatchRequestBody();
requestBody.setConsumerGroup(this.consumerGroup);
requestBody.setClientId(this.mQClientFactory.getClientId());
requestBody.setMqSet(mqs);
try {
Set<MessageQueue> lockOKMQSet =
this.mQClientFactory.getMQClientAPIImpl().lockBatchMQ(findBrokerResult.getBrokerAddr(), requestBody, 1000);
for (MessageQueue mq : lockOKMQSet) {
ProcessQueue processQueue = this.processQueueTable.get(mq);
if (processQueue != null) {
if (!processQueue.isLocked()) {
log.info("the message queue locked OK, Group: {} {}", this.consumerGroup, mq);
}
processQueue.setLocked(true);
processQueue.setLastLockTimestamp(System.currentTimeMillis());
}
}
for (MessageQueue mq : mqs) {
if (!lockOKMQSet.contains(mq)) {
ProcessQueue processQueue = this.processQueueTable.get(mq);
if (processQueue != null) {
processQueue.setLocked(false);
log.warn("the message queue locked Failed, Group: {} {}", this.consumerGroup, mq);
}
}
}
} catch (Exception e) {
log.error("lockBatchMQ exception, " + mqs, e);
}
}
}
}这个方法的逻辑很清晰，先遍历所有的brokerName，根据brokerName在客户端本地查找到对应的broker的地址，然后根据消费者组名，消费者客户端id，对应broker下的消息队列集合，跟broker地址，通过MQClientAPIInstance发送给broker，获得到需要加锁的消费者队列集合。然后遍历对应消息队列，将processQueueTable中需要加锁的消息队列setLock(true)加锁，不需要加锁的消息队列setLock(false)解锁。需要提一下，该定时任务1s触发一次。
回到defaultMQPushConsumerImpl的start()方法，然后将当前消费者组名与DefaultMQConsumerImpl以键值对形式注册到消费者实例中。然后执行MQClientInstance的start()方法
public void start() throws MQClientException {
synchronized (this) {
switch (this.serviceState) {
case CREATE_JUST:
this.serviceState = ServiceState.START_FAILED;
// If not specified,looking address from name server
if (null == this.clientConfig.getNamesrvAddr()) {
this.mQClientAPIImpl.fetchNameServerAddr();
}
// Start request-response channel
this.mQClientAPIImpl.start();
// Start various schedule tasks
this.startScheduledTask();
// Start pull service
this.pullMessageService.start();
// Start rebalance service
this.rebalanceService.start();
// Start push service
this.defaultMQProducer.getDefaultMQProducerImpl().start(false);
log.info("the client factory [{}] start OK", this.clientId);
this.serviceState = ServiceState.RUNNING;
break;
case RUNNING:
break;
case SHUTDOWN_ALREADY:
break;
case START_FAILED:
throw new MQClientException("The Factory object[" + this.getClientId() + "] has been created before
, and failed.", null);
default:
break;
}
}
}如果一开始没有配置nameServer的地址，那么主动去请求nameserver的地址，接下来是netty客户端的启动。
接下来是五个定时任务的启动
private void startScheduledTask() {
if (null == this.clientConfig.getNamesrvAddr()) {
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
MQClientInstance.this.mQClientAPIImpl.fetchNameServerAddr();
} catch (Exception e) {
log.error("ScheduledTask fetchNameServerAddr exception", e);
}
}
}, 1000 * 10, 1000 * 60 * 2, TimeUnit.MILLISECONDS);
}
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
MQClientInstance.this.updateTopicRouteInfoFromNameServer();
} catch (Exception e) {
log.error("ScheduledTask updateTopicRouteInfoFromNameServer exception", e);
}
}
}, 10, this.clientConfig.getPollNameServerInterval(), TimeUnit.MILLISECONDS);
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
MQClientInstance.this.cleanOfflineBroker();
MQClientInstance.this.sendHeartbeatToAllBrokerWithLock();
} catch (Exception e) {
log.error("ScheduledTask sendHeartbeatToAllBroker exception", e);
}
}
}, 1000, this.clientConfig.getHeartbeatBrokerInterval(), TimeUnit.MILLISECONDS);
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
MQClientInstance.this.persistAllConsumerOffset();
} catch (Exception e) {
log.error("ScheduledTask persistAllConsumerOffset exception", e);
}
}
}, 1000 * 10, this.clientConfig.getPersistConsumerOffsetInterval(), TimeUnit.MILLISECONDS);
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
MQClientInstance.this.adjustThreadPool();
} catch (Exception e) {
log.error("ScheduledTask adjustThreadPool exception", e);
}
}
}, 1, 1, TimeUnit.MINUTES);
}
1、如果客户端配置仍旧没有设置相关的地址服务地址，会每隔10秒去尝试获取一次地址服务的地址。
2、定时从nameserver中获取并更新本地路由信息
3、清除掉线的broker跟心跳
4、定时持久化消费进度offset
5、调整线程池线程数目
1跟2之前的分析过，我们看下4，每隔10s对每个消息队列的消费进度进行持久化，通过persistAllConsumer()方法
private void persistAllConsumerOffset() {
Iterator<Entry<String, MQConsumerInner>> it = this.consumerTable.entrySet().iterator();
while (it.hasNext()) {
Entry<String, MQConsumerInner> entry = it.next();
MQConsumerInner impl = entry.getValue();
impl.persistConsumerOffset();
}
} @Override
public void persistConsumerOffset() {
try {
this.makeSureStateOK();
Set<MessageQueue> mqs = new HashSet<MessageQueue>();
Set<MessageQueue> allocateMq = this.rebalanceImpl.getProcessQueueTable().keySet();
mqs.addAll(allocateMq);
this.offsetStore.persistAll(mqs);
} catch (Exception e) {
log.error("group: " + this.defaultMQPushConsumer.getConsumerGroup() + " persistConsumerOffset exception", e);
}
} public void persistAll(Set<MessageQueue> mqs) {
if (null == mqs || mqs.isEmpty())
return;
OffsetSerializeWrapper offsetSerializeWrapper = new OffsetSerializeWrapper();
for (Map.Entry<MessageQueue, AtomicLong> entry : this.offsetTable.entrySet()) {
if (mqs.contains(entry.getKey())) {
AtomicLong offset = entry.getValue();
offsetSerializeWrapper.getOffsetTable().put(entry.getKey(), offset);
}
}
String jsonString = offsetSerializeWrapper.toJson(true);
if (jsonString != null) {
try {
MixAll.string2File(jsonString, this.storePath);
} catch (IOException e) {
log.error("persistAll consumer offset Exception, " + this.storePath, e);
}
}
}遍历offsetTable，将其键值对复制到新创建的负责序列化的offsetSerializeWrapper对象中，offsetSerializeWrapper将其内容转成json格式的字符串，再调用工具类，将字符串写入到本地文件中。
我们再看看集群模式下RemoteBrokerOffsetStore的persistAll方法
@Override
public void persistAll(Set<MessageQueue> mqs) {
if (null == mqs || mqs.isEmpty())
return;
final HashSet<MessageQueue> unusedMQ = new HashSet<MessageQueue>();
if (!mqs.isEmpty()) {
for (Map.Entry<MessageQueue, AtomicLong> entry : this.offsetTable.entrySet()) {
MessageQueue mq = entry.getKey();
AtomicLong offset = entry.getValue();
if (offset != null) {
if (mqs.contains(mq)) {
try {
this.updateConsumeOffsetToBroker(mq, offset.get());
log.info("[persistAll] Group: {} ClientId: {} updateConsumeOffsetToBroker {} {}",
this.groupName,
this.mQClientFactory.getClientId(),
mq,
offset.get());
} catch (Exception e) {
log.error("updateConsumeOffsetToBroker exception, " + mq.toString(), e);
}
} else {
unusedMQ.add(mq);
}
}
}
}
if (!unusedMQ.isEmpty()) {
for (MessageQueue mq : unusedMQ) {
this.offsetTable.remove(mq);
log.info("remove unused mq, {}, {}", mq, this.groupName);
}
}
}统计出offsetTable中的不在传入的mqs中的消息队列，从offsetTable中移除它们。遍历offsetTable，并offset不为null且将在mqs中的每条消息队列调用updateConsumeOffsetToBroker达到在远程更新每条mq的消费进度的目的。当然updateConsumeOffsetToBroker内部还是通过nettyRemotingClient的方式，且RequestCommand为UPDATE_CONSUMER_OFFSET。
接下来启动pullMessageService，我们来看其run方法
@Override
public void run() {
log.info(this.getServiceName() + " service started");
while (!this.isStopped()) {
try {
PullRequest pullRequest = this.pullRequestQueue.take();
if (pullRequest != null) {
this.pullMessage(pullRequest);
}
} catch (InterruptedException e) {
} catch (Exception e) {
log.error("Pull Message Service Run Method exception", e);
}
}
log.info(this.getServiceName() + " service end");
}逻辑很简单，不断从pullRequestQueue阻塞队列中获取元素，如果得到元素且不为null，那么调用pullMessage将得到的pullRequest传入。
我们先重点看下rebalanceService，这里是rebalanceService的启动。我们看其run方法
@Override
public void run() {
log.info(this.getServiceName() + " service started");
while (!this.isStopped()) {
this.waitForRunning(waitInterval);
this.mqClientFactory.doRebalance();
}
log.info(this.getServiceName() + " service end");
} public void doRebalance() {
for (Map.Entry<String, MQConsumerInner> entry : this.consumerTable.entrySet()) {
MQConsumerInner impl = entry.getValue();
if (impl != null) {
try {
impl.doRebalance();
} catch (Throwable e) {
log.error("doRebalance exception", e);
}
}
}
} @Override
public void doRebalance() {
if (!this.pause) {
this.rebalanceImpl.doRebalance(this.isConsumeOrderly());
}
}这里传入了是否是顺序调用，而pull客户端默认传入false，具体实现在RebalanceImpl中
public void doRebalance(final boolean isOrder) {
Map<String, SubscriptionData> subTable = this.getSubscriptionInner();
if (subTable != null) {
for (final Map.Entry<String, SubscriptionData> entry : subTable.entrySet()) {
final String topic = entry.getKey();
try {
this.rebalanceByTopic(topic, isOrder);
} catch (Throwable e) {
if (!topic.startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
log.warn("rebalanceByTopic Exception", e);
}
}
}
}
this.truncateMessageQueueNotMyTopic();
} private void rebalanceByTopic(final String topic, final boolean isOrder) {
switch (messageModel) {
case BROADCASTING: {
Set<MessageQueue> mqSet = this.topicSubscribeInfoTable.get(topic);
if (mqSet != null) {
boolean changed = this.updateProcessQueueTableInRebalance(topic, mqSet, isOrder);
if (changed) {
this.messageQueueChanged(topic, mqSet, mqSet);
log.info("messageQueueChanged {} {} {} {}",
consumerGroup,
topic,
mqSet,
mqSet);
}
} else {
log.warn("doRebalance, {}, but the topic[{}] not exist.", consumerGroup, topic);
}
break;
}
case CLUSTERING: {
Set<MessageQueue> mqSet = this.topicSubscribeInfoTable.get(topic);
List<String> cidAll = this.mQClientFactory.findConsumerIdList(topic, consumerGroup);
if (null == mqSet) {
if (!topic.startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
log.warn("doRebalance, {}, but the topic[{}] not exist.", consumerGroup, topic);
}
}
if (null == cidAll) {
log.warn("doRebalance, {} {}, get consumer id list failed", consumerGroup, topic);
}
if (mqSet != null && cidAll != null) {
List<MessageQueue> mqAll = new ArrayList<MessageQueue>();
mqAll.addAll(mqSet);
Collections.sort(mqAll);
Collections.sort(cidAll);
AllocateMessageQueueStrategy strategy = this.allocateMessageQueueStrategy;
List<MessageQueue> allocateResult = null;
try {
allocateResult = strategy.allocate(
this.consumerGroup,
this.mQClientFactory.getClientId(),
mqAll,
cidAll);
} catch (Throwable e) {
log.error("AllocateMessageQueueStrategy.allocate Exception. allocateMessageQueueStrategyName={}",
strategy.getName(), e);
return;
}
Set<MessageQueue> allocateResultSet = new HashSet<MessageQueue>();
if (allocateResult != null) {
allocateResultSet.addAll(allocateResult);
}
boolean changed = this.updateProcessQueueTableInRebalance(topic, allocateResultSet, isOrder);
if (changed) {
log.info(
"rebalanced result changed. allocateMessageQueueStrategyName={}, group={}, topic={}, clientId={},
mqAllSize={}, cidAllSize={}, rebalanceResultSize={}, rebalanceResultSet={}",
strategy.getName(), consumerGroup, topic, this.mQClientFactory.getClientId(), mqSet.size(), cidAll.size(),
allocateResultSet.size(), allocateResultSet);
this.messageQueueChanged(topic, mqSet, allocateResultSet);
}
}
break;
}
default:
break;
}
}这段代码其实在pull的时候解释过。在广播模式下，所有的消费者都将应收到所订阅的topic的消息，就直接拿所有的消息队列去更新processQueue的数据，如果在集群模式下那么需要使用负载均衡策略分配消息队列，在一开始会配置好负载均衡策略，然后拿着分配到的消息队列去更新消费者的processQueue的数据。通过updateProcessQueueTableInRebalance()方法更新。
private boolean updateProcessQueueTableInRebalance(final String topic, final Set<MessageQueue> mqSet,
final boolean isOrder) {
boolean changed = false;
Iterator<Entry<MessageQueue, ProcessQueue>> it = this.processQueueTable.entrySet().iterator();
while (it.hasNext()) {
Entry<MessageQueue, ProcessQueue> next = it.next();
MessageQueue mq = next.getKey();
ProcessQueue pq = next.getValue();
if (mq.getTopic().equals(topic)) {
if (!mqSet.contains(mq)) {
pq.setDropped(true);
if (this.removeUnnecessaryMessageQueue(mq, pq)) {
it.remove();
changed = true;
log.info("doRebalance, {}, remove unnecessary mq, {}", consumerGroup, mq);
}
} else if (pq.isPullExpired()) {
switch (this.consumeType()) {
case CONSUME_ACTIVELY:
break;
case CONSUME_PASSIVELY:
pq.setDropped(true);
if (this.removeUnnecessaryMessageQueue(mq, pq)) {
it.remove();
changed = true;
log.error("[BUG]doRebalance, {}, remove unnecessary mq, {}, because pull is pause, so try to fixed it",
consumerGroup, mq);
}
break;
default:
break;
}
}
}
}
List<PullRequest> pullRequestList = new ArrayList<PullRequest>();
for (MessageQueue mq : mqSet) {
if (!this.processQueueTable.containsKey(mq)) {
if (isOrder && !this.lock(mq)) {
log.warn("doRebalance, {}, add a new mq failed, {}, because lock failed", consumerGroup, mq);
continue;
}
this.removeDirtyOffset(mq);
ProcessQueue pq = new ProcessQueue();
long nextOffset = this.computePullFromWhere(mq);
if (nextOffset >= 0) {
ProcessQueue pre = this.processQueueTable.putIfAbsent(mq, pq);
if (pre != null) {
log.info("doRebalance, {}, mq already exists, {}", consumerGroup, mq);
} else {
log.info("doRebalance, {}, add a new mq, {}", consumerGroup, mq);
PullRequest pullRequest = new PullRequest();
pullRequest.setConsumerGroup(consumerGroup);
pullRequest.setNextOffset(nextOffset);
pullRequest.setMessageQueue(mq);
pullRequest.setProcessQueue(pq);
pullRequestList.add(pullRequest);
changed = true;
}
} else {
log.warn("doRebalance, {}, add new mq failed, {}", consumerGroup, mq);
}
}
}
this.dispatchPullRequest(pullRequestList);
return changed;
} @Override
public void dispatchPullRequest(List<PullRequest> pullRequestList) {
for (PullRequest pullRequest : pullRequestList) {
this.defaultMQPushConsumerImpl.executePullRequestImmediately(pullRequest);
log.info("doRebalance, {}, add a new pull request {}", consumerGroup, pullRequest);
}
} public void executePullRequestImmediately(final PullRequest pullRequest) {
this.mQClientFactory.getPullMessageService().executePullRequestImmediately(pullRequest);
}继续把pullRequest传入到mqClientInstance的pullMessageService调用executePullRequestImmediately()方法来实现。
我们之前分析到pullMessageService的run方法中，不断从pullRequestQueue阻塞队列中获取元素，那么pullRequestQueue阻塞队列中的元素是什么时候被放进来的？在这里我们可以看到，由rebalanceImpl调用的executePullRequestImmediately()方法，将pullRequest加入了阻塞队列。
public void executePullRequestImmediately(final PullRequest pullRequest) {
try {
this.pullRequestQueue.put(pullRequest);
} catch (InterruptedException e) {
log.error("executePullRequestImmediately pullRequestQueue.put", e);
}
} private void pullMessage(final PullRequest pullRequest) {
final MQConsumerInner consumer = this.mQClientFactory.selectConsumer(pullRequest.getConsumerGroup());
if (consumer != null) {
DefaultMQPushConsumerImpl impl = (DefaultMQPushConsumerImpl) consumer;
impl.pullMessage(pullRequest);
} else {
log.warn("No matched consumer for the PullRequest {}, drop it", pullRequest);
}
} public void pullMessage(final PullRequest pullRequest) {
final ProcessQueue processQueue = pullRequest.getProcessQueue();
if (processQueue.isDropped()) {
log.info("the pull request[{}] is dropped.", pullRequest.toString());
return;
}
pullRequest.getProcessQueue().setLastPullTimestamp(System.currentTimeMillis());
try {
this.makeSureStateOK();
} catch (MQClientException e) {
log.warn("pullMessage exception, consumer state not ok", e);
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_EXCEPTION);
return;
}
if (this.isPause()) {
log.warn("consumer was paused, execute pull request later. instanceName={}, group={}",
this.defaultMQPushConsumer.getInstanceName(), this.defaultMQPushConsumer.getConsumerGroup());
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_SUSPEND);
return;
}
long cachedMessageCount = processQueue.getMsgCount().get();
long cachedMessageSizeInMiB = processQueue.getMsgSize().get() / (1024 * 1024);
if (cachedMessageCount > this.defaultMQPushConsumer.getPullThresholdForQueue()) {
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);
if ((queueFlowControlTimes++ % 1000) == 0) {
log.warn(
"the cached message count exceeds the threshold {}, so do flow control, minOffset={}, maxOffset={},
count={}, size={} MiB, pullRequest={}, flowControlTimes={}",
this.defaultMQPushConsumer.getPullThresholdForQueue(), processQueue.getMsgTreeMap().firstKey(),
processQueue.getMsgTreeMap().lastKey(), cachedMessageCount, cachedMessageSizeInMiB, pullRequest,
queueFlowControlTimes);
}
return;
}
if (cachedMessageSizeInMiB > this.defaultMQPushConsumer.getPullThresholdSizeForQueue()) {
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);
if ((queueFlowControlTimes++ % 1000) == 0) {
log.warn(
"the cached message size exceeds the threshold {} MiB, so do flow control, minOffset={}, maxOffset={}
, count={}, size={} MiB, pullRequest={}, flowControlTimes={}",
this.defaultMQPushConsumer.getPullThresholdSizeForQueue(), processQueue.getMsgTreeMap().firstKey()
, processQueue.getMsgTreeMap().lastKey(), cachedMessageCount, cachedMessageSizeInMiB, pullRequest, queueFlowControlTimes);
}
return;
}
if (!this.consumeOrderly) {
if (processQueue.getMaxSpan() > this.defaultMQPushConsumer.getConsumeConcurrentlyMaxSpan()) {
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_FLOW_CONTROL);
if ((queueMaxSpanFlowControlTimes++ % 1000) == 0) {
log.warn(
"the queue's messages, span too long, so do flow control, minOffset={}, maxOffset={}, maxSpan={}, pullRequest={}
, flowControlTimes={}",
processQueue.getMsgTreeMap().firstKey(), processQueue.getMsgTreeMap().lastKey(), processQueue.getMaxSpan(),
pullRequest, queueMaxSpanFlowControlTimes);
}
return;
}
} else {
if (processQueue.isLocked()) {
if (!pullRequest.isLockedFirst()) {
final long offset = this.rebalanceImpl.computePullFromWhere(pullRequest.getMessageQueue());
boolean brokerBusy = offset < pullRequest.getNextOffset();
log.info("the first time to pull message, so fix offset from broker. pullRequest: {} NewOffset: {} brokerBusy: {}",
pullRequest, offset, brokerBusy);
if (brokerBusy) {
log.info("[NOTIFYME]the first time to pull message, but pull request offset larger
than broker consume offset. pullRequest: {} NewOffset: {}",
pullRequest, offset);
}
pullRequest.setLockedFirst(true);
pullRequest.setNextOffset(offset);
}
} else {
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_EXCEPTION);
log.info("pull message later because not locked in broker, {}", pullRequest);
return;
}
}
final SubscriptionData subscriptionData = this.rebalanceImpl.getSubscriptionInner().get(pullRequest.getMessageQueue().getTopic());
if (null == subscriptionData) {
// 由于并发关系，即使找不到订阅关系，也要重试下，防止丢失PullRequest
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_EXCEPTION);
log.warn("find the consumer's subscription failed, {}", pullRequest);
return;
}
final long beginTimestamp = System.currentTimeMillis();
PullCallback pullCallback = new PullCallback() {
@Override
public void onSuccess(PullResult pullResult) {
if (pullResult != null) {
pullResult = DefaultMQPushConsumerImpl.this.pullAPIWrapper.processPullResult(pullRequest.getMessageQueue(),
pullResult, subscriptionData);
switch (pullResult.getPullStatus()) {
case FOUND:
long prevRequestOffset = pullRequest.getNextOffset();
pullRequest.setNextOffset(pullResult.getNextBeginOffset());
long pullRT = System.currentTimeMillis() - beginTimestamp;
DefaultMQPushConsumerImpl.this.getConsumerStatsManager().incPullRT(pullRequest.getConsumerGroup(),
pullRequest.getMessageQueue().getTopic(), pullRT);
long firstMsgOffset = Long.MAX_VALUE;
if (pullResult.getMsgFoundList() == null || pullResult.getMsgFoundList().isEmpty()) {
DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
} else {
firstMsgOffset = pullResult.getMsgFoundList().get(0).getQueueOffset();
DefaultMQPushConsumerImpl.this.getConsumerStatsManager().incPullTPS(pullRequest.getConsumerGroup(),
pullRequest.getMessageQueue().getTopic(), pullResult.getMsgFoundList().size());
boolean dispathToConsume = processQueue.putMessage(pullResult.getMsgFoundList());
DefaultMQPushConsumerImpl.this.consumeMessageService.submitConsumeRequest(
pullResult.getMsgFoundList(),
processQueue,
pullRequest.getMessageQueue(),
dispathToConsume);
if (DefaultMQPushConsumerImpl.this.defaultMQPushConsumer.getPullInterval() > 0) {
DefaultMQPushConsumerImpl.this.executePullRequestLater(pullRequest,
DefaultMQPushConsumerImpl.this.defaultMQPushConsumer.getPullInterval());
} else {
DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
}
}
if (pullResult.getNextBeginOffset() < prevRequestOffset
|| firstMsgOffset < prevRequestOffset) {
log.warn(
"[BUG] pull message result maybe data wrong, nextBeginOffset: {} firstMsgOffset:
{} prevRequestOffset: {}",
pullResult.getNextBeginOffset(),
firstMsgOffset,
prevRequestOffset);
}
break;
case NO_NEW_MSG:
pullRequest.setNextOffset(pullResult.getNextBeginOffset());
DefaultMQPushConsumerImpl.this.correctTagsOffset(pullRequest);
DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
break;
case NO_MATCHED_MSG:
pullRequest.setNextOffset(pullResult.getNextBeginOffset());
DefaultMQPushConsumerImpl.this.correctTagsOffset(pullRequest);
DefaultMQPushConsumerImpl.this.executePullRequestImmediately(pullRequest);
break;
case OFFSET_ILLEGAL:
log.warn("the pull request offset illegal, {} {}",
pullRequest.toString(), pullResult.toString());
pullRequest.setNextOffset(pullResult.getNextBeginOffset());
pullRequest.getProcessQueue().setDropped(true);
DefaultMQPushConsumerImpl.this.executeTaskLater(new Runnable() {
@Override
public void run() {
try {
DefaultMQPushConsumerImpl.this.offsetStore.updateOffset(pullRequest.getMessageQueue(),
pullRequest.getNextOffset(), false);
DefaultMQPushConsumerImpl.this.offsetStore.persist(pullRequest.getMessageQueue());
DefaultMQPushConsumerImpl.this.rebalanceImpl.removeProcessQueue(pullRequest.getMessageQueue());
log.warn("fix the pull request offset, {}", pullRequest);
} catch (Throwable e) {
log.error("executeTaskLater Exception", e);
}
}
}, 10000);
break;
default:
break;
}
}
}
@Override
public void onException(Throwable e) {
if (!pullRequest.getMessageQueue().getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
log.warn("execute the pull request exception", e);
}
DefaultMQPushConsumerImpl.this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_EXCEPTION);
}
};
boolean commitOffsetEnable = false;
long commitOffsetValue = 0L;
if (MessageModel.CLUSTERING == this.defaultMQPushConsumer.getMessageModel()) {
commitOffsetValue = this.offsetStore.readOffset(pullRequest.getMessageQueue(), ReadOffsetType.READ_FROM_MEMORY);
if (commitOffsetValue > 0) {
commitOffsetEnable = true;
}
}
String subExpression = null;
boolean classFilter = false;
SubscriptionData sd = this.rebalanceImpl.getSubscriptionInner().get(pullRequest.getMessageQueue().getTopic());
if (sd != null) {
if (this.defaultMQPushConsumer.isPostSubscriptionWhenPull() && !sd.isClassFilterMode()) {
subExpression = sd.getSubString();
}
classFilter = sd.isClassFilterMode();
}
int sysFlag = PullSysFlag.buildSysFlag(
commitOffsetEnable, // commitOffset
true, // suspend
subExpression != null, // subscription
classFilter // class filter
);
try {
this.pullAPIWrapper.pullKernelImpl(
pullRequest.getMessageQueue(),
subExpression,
subscriptionData.getExpressionType(),
subscriptionData.getSubVersion(),
pullRequest.getNextOffset(),
this.defaultMQPushConsumer.getPullBatchSize(),
sysFlag,
commitOffsetValue,
BROKER_SUSPEND_MAX_TIME_MILLIS,
CONSUMER_TIMEOUT_MILLIS_WHEN_SUSPEND,
CommunicationMode.ASYNC,
pullCallback
);
} catch (Exception e) {
log.error("pullKernelImpl exception", e);
this.executePullRequestLater(pullRequest, PULL_TIME_DELAY_MILLS_WHEN_EXCEPTION);
}
}这里先得到pullRequest里封装的processQueue，更新processQueue的最新pull时间戳为当前时间。调用makeSureOk()来确定当前消费者客户端的状态，确定不是中止的状态，接下来是对于流量控制消费者状态消息长度等一系列的判断，如果不符合配置要求，那么把pullRequest丢入定时任务中，稍后调用executePullRequestImmediately()，即把pullRequest重新塞入阻塞队列，等待下次执行。如果不是顺序执行，那么当并发量大于配置时，稍后重新尝试，如果是顺序执行，当前线程没获得锁，那么稍后重新执行，否则，计算当前的offset并存入pullRequest的nextOffset成员中。
接下来是pullCallBack的生成，push采用异步发送方式，当接收到broker的回复的消息后，会调用这里pullCallBack的onSucess方法或者onException方法。
如果是广播模式，如果从内存中找到对应的消息队列的offset不为null且大于0，那么commitOffsetEnable设为true。然后根据消息队列跟topic得到对应的topic订阅消息，判断其是否是classFilterMode模式，然后构造标志量sysFlag。接下来异步发送消息跟pull发送消息流程一样。
我们回到消息回调部分，如果消息接收失败，那么进入到onException()方法，这里无非把PullRequest扔回阻塞队列，稍后执行，如果消息接收成功，那么进入到onSucess()方法中，那么先通过processPullResult()方法对接收到的消息进行反序列化跟过滤。然后根据PullResult的状态，如果没有新的消息，或者没有匹配的消息，或者offset格式不合法，那么都按照原先的NextBeginOffset的位置重新更新其offset，并将pullRequest重新放入消息队列稍后重新执行，只有在FOUND状态并且没有被tag过滤掉的新的消息，那么调用processQueue的putMessage()方法并将其反序列化了的拉取过来的没有被tag过滤掉的新的消息存放在processQueue里的msgTreeMap当中。
public boolean putMessage(final List<MessageExt> msgs) {
boolean dispatchToConsume = false;
try {
this.lockTreeMap.writeLock().lockInterruptibly();
try {
int validMsgCnt = 0;
for (MessageExt msg : msgs) {
MessageExt old = msgTreeMap.put(msg.getQueueOffset(), msg);
if (null == old) {
validMsgCnt++;
this.queueOffsetMax = msg.getQueueOffset();
msgSize.addAndGet(msg.getBody().length);
}
}
msgCount.addAndGet(validMsgCnt);
if (!msgTreeMap.isEmpty() && !this.consuming) {
dispatchToConsume = true;
this.consuming = true;
}
if (!msgs.isEmpty()) {
MessageExt messageExt = msgs.get(msgs.size() - 1);
String property = messageExt.getProperty(MessageConst.PROPERTY_MAX_OFFSET);
if (property != null) {
long accTotal = Long.parseLong(property) - messageExt.getQueueOffset();
if (accTotal > 0) {
this.msgAccCnt = accTotal;
}
}
}
} finally {
this.lockTreeMap.writeLock().unlock();
}
} catch (InterruptedException e) {
log.error("putMessage exception", e);
}
return dispatchToConsume;
}这里加锁，将取来的消息存放在msgTreeMap中，以offset为键，消息为value这样的键值对确保了取来的消息准确，并且统计新加进来消息数量，如果没有消费过，那么把dispatchToConsume设为true。接下来就是消息的消费。
接下来调用defaultMQPushConsumerImpl下的ConsumeMessageService的submitConsumeRequest()方法来消费。
关于ConsumeMessageService，之前已经分析过，如果配置了同步的话，ConsumeMessageService赋值为ConsumeMessageOrderlyService的实例，应该还记得之前分析过它的start方法，定时对需要加锁的mq加锁。下面来看下其submitConsumeRequest方法
@Override
public void submitConsumeRequest(
final List<MessageExt> msgs,
final ProcessQueue processQueue,
final MessageQueue messageQueue,
final boolean dispathToConsume) {
if (dispathToConsume) {
ConsumeRequest consumeRequest = new ConsumeRequest(processQueue, messageQueue);
this.consumeExecutor.submit(consumeRequest);
}
}因为这里是顺序执行，所以调用了肯定单线程执行，如果分发即dispathToConsume为true，那么直接把processQueue、messageQueue封装成ConsumeRequest消费请求丢入线程池中进行消费。
我们再看下非顺序即ConsumeMessageOrderlyService的submitConsumeRequest方法
@Override
public void submitConsumeRequest(
final List<MessageExt> msgs,
final ProcessQueue processQueue,
final MessageQueue messageQueue,
final boolean dispatchToConsume) {
final int consumeBatchSize = this.defaultMQPushConsumer.getConsumeMessageBatchMaxSize();
if (msgs.size() <= consumeBatchSize) {
ConsumeRequest consumeRequest = new ConsumeRequest(msgs, processQueue, messageQueue);
try {
this.consumeExecutor.submit(consumeRequest);
} catch (RejectedExecutionException e) {
this.submitConsumeRequestLater(consumeRequest);
}
} else {
for (int total = 0; total < msgs.size(); ) {
List<MessageExt> msgThis = new ArrayList<MessageExt>(consumeBatchSize);
for (int i = 0; i < consumeBatchSize; i++, total++) {
if (total < msgs.size()) {
msgThis.add(msgs.get(total));
} else {
break;
}
}
ConsumeRequest consumeRequest = new ConsumeRequest(msgThis, processQueue, messageQueue);
try {
this.consumeExecutor.submit(consumeRequest);
} catch (RejectedExecutionException e) {
for (; total < msgs.size(); total++) {
msgThis.add(msgs.get(total));
}
this.submitConsumeRequestLater(consumeRequest);
}
}
}
}
@Override
public void run() {
if (this.processQueue.isDropped()) {
log.info("the message queue not be able to consume, because it's dropped. group={} {}",
ConsumeMessageConcurrentlyService.this.consumerGroup, this.messageQueue);
return;
}
MessageListenerConcurrently listener = ConsumeMessageConcurrentlyService.this.messageListener;
ConsumeConcurrentlyContext context = new ConsumeConcurrentlyContext(messageQueue);
ConsumeConcurrentlyStatus status = null;
ConsumeMessageContext consumeMessageContext = null;
if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
consumeMessageContext = new ConsumeMessageContext();
consumeMessageContext.setConsumerGroup(defaultMQPushConsumer.getConsumerGroup());
consumeMessageContext.setProps(new HashMap<String, String>());
consumeMessageContext.setMq(messageQueue);
consumeMessageContext.setMsgList(msgs);
consumeMessageContext.setSuccess(false);
ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.executeHookBefore(consumeMessageContext);
}
long beginTimestamp = System.currentTimeMillis();
boolean hasException = false;
ConsumeReturnType returnType = ConsumeReturnType.SUCCESS;
try {
ConsumeMessageConcurrentlyService.this.resetRetryTopic(msgs);
if (msgs != null && !msgs.isEmpty()) {
for (MessageExt msg : msgs) {
MessageAccessor.setConsumeStartTimeStamp(msg, String.valueOf(System.currentTimeMillis()));
}
}
status = listener.consumeMessage(Collections.unmodifiableList(msgs), context);
} catch (Throwable e) {
log.warn("consumeMessage exception: {} Group: {} Msgs: {} MQ: {}",
RemotingHelper.exceptionSimpleDesc(e),
ConsumeMessageConcurrentlyService.this.consumerGroup,
msgs,
messageQueue);
hasException = true;
}
long consumeRT = System.currentTimeMillis() - beginTimestamp;
if (null == status) {
if (hasException) {
returnType = ConsumeReturnType.EXCEPTION;
} else {
returnType = ConsumeReturnType.RETURNNULL;
}
} else if (consumeRT >= defaultMQPushConsumer.getConsumeTimeout() * 60 * 1000) {
returnType = ConsumeReturnType.TIME_OUT;
} else if (ConsumeConcurrentlyStatus.RECONSUME_LATER == status) {
returnType = ConsumeReturnType.FAILED;
} else if (ConsumeConcurrentlyStatus.CONSUME_SUCCESS == status) {
returnType = ConsumeReturnType.SUCCESS;
}
if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
consumeMessageContext.getProps().put(MixAll.CONSUME_CONTEXT_TYPE, returnType.name());
}
if (null == status) {
log.warn("consumeMessage return null, Group: {} Msgs: {} MQ: {}",
ConsumeMessageConcurrentlyService.this.consumerGroup,
msgs,
messageQueue);
status = ConsumeConcurrentlyStatus.RECONSUME_LATER;
}
if (ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.hasHook()) {
consumeMessageContext.setStatus(status.toString());
consumeMessageContext.setSuccess(ConsumeConcurrentlyStatus.CONSUME_SUCCESS == status);
ConsumeMessageConcurrentlyService.this.defaultMQPushConsumerImpl.executeHookAfter(consumeMessageContext);
}
ConsumeMessageConcurrentlyService.this.getConsumerStatsManager()
.incConsumeRT(ConsumeMessageConcurrentlyService.this.consumerGroup, messageQueue.getTopic(), consumeRT);
if (!processQueue.isDropped()) {
ConsumeMessageConcurrentlyService.this.processConsumeResult(status, context, this);
} else {
log.warn("processQueue is dropped without process consume result. messageQueue={}, msgs={}", messageQueue, msgs);
}
} public void processConsumeResult(
final ConsumeConcurrentlyStatus status,
final ConsumeConcurrentlyContext context,
final ConsumeRequest consumeRequest
) {
int ackIndex = context.getAckIndex();
if (consumeRequest.getMsgs().isEmpty())
return;
switch (status) {
case CONSUME_SUCCESS:
if (ackIndex >= consumeRequest.getMsgs().size()) {
ackIndex = consumeRequest.getMsgs().size() - 1;
}
int ok = ackIndex + 1;
int failed = consumeRequest.getMsgs().size() - ok;
this.getConsumerStatsManager().incConsumeOKTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), ok);
this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(), failed);
break;
case RECONSUME_LATER:
ackIndex = -1;
this.getConsumerStatsManager().incConsumeFailedTPS(consumerGroup, consumeRequest.getMessageQueue().getTopic(),
consumeRequest.getMsgs().size());
break;
default:
break;
}
switch (this.defaultMQPushConsumer.getMessageModel()) {
case BROADCASTING:
for (int i = ackIndex + 1; i < consumeRequest.getMsgs().size(); i++) {
MessageExt msg = consumeRequest.getMsgs().get(i);
log.warn("BROADCASTING, the message consume failed, drop it, {}", msg.toString());
}
break;
case CLUSTERING:
List<MessageExt> msgBackFailed = new ArrayList<MessageExt>(consumeRequest.getMsgs().size());
for (int i = ackIndex + 1; i < consumeRequest.getMsgs().size(); i++) {
MessageExt msg = consumeRequest.getMsgs().get(i);
boolean result = this.sendMessageBack(msg, context);
if (!result) {
msg.setReconsumeTimes(msg.getReconsumeTimes() + 1);
msgBackFailed.add(msg);
}
}
if (!msgBackFailed.isEmpty()) {
consumeRequest.getMsgs().removeAll(msgBackFailed);
this.submitConsumeRequestLater(msgBackFailed, consumeRequest.getProcessQueue(), consumeRequest.getMessageQueue());
}
break;
default:
break;
}
long offset = consumeRequest.getProcessQueue().removeMessage(consumeRequest.getMsgs());
if (offset >= 0 && !consumeRequest.getProcessQueue().isDropped()) {
this.defaultMQPushConsumerImpl.getOffsetStore().updateOffset(consumeRequest.getMessageQueue(), offset, true);
}
}如果成功，那么对其消费的数量ackIndex进行设置，如果失败则ackIndex设为-1，后面根据消息模式进行不同的处理，如果是广播模式，仅仅记录日志，不处理。如果是集群模式，先调用sendMessageBack把消息向broker发送回去，如果失败了那么将会将这条消息扔进定时任务中稍后重新消费，并清空失败消息队列。
最后从processQueue中的treeMap中移除消费了消息，并得到offset，更新消息队列的offset。
到这里基本上把其PushConsumer的启动全流程讲完了，也分析了它是如何自动地push消息，让listener处理。