本文主要分析RocketMQ中Producer的啓動過程。
RocketMQ的版本爲:4.2.0 release。
一.時序圖
根據源碼,把Producer啓動過程的時序圖畫了一遍:
二.源碼分析
1 start() :DefaultMQProducer啓動。
DefaultMQProducer主要功能都是在DefaultMQProducerImpl中實現的。類似的,DefaultMQPushConsumer的大部分功能也在DefaultMQPushConsumerImpl中實現:
//DefaultMQProducer#start
public void start() throws MQClientException {
this.defaultMQProducerImpl.start();
}
1.1 checkConfig:檢查producerGroup是否合法。
// DefaultMQProducerImpl#checkConfig
private void checkConfig() throws MQClientException {
Validators.checkGroup(this.defaultMQProducer.getProducerGroup());
if (null == this.defaultMQProducer.getProducerGroup()) {
throw new MQClientException("producerGroup is null", null);
}
if (this.defaultMQProducer.getProducerGroup().equals(MixAll.DEFAULT_PRODUCER_GROUP)) {// 不能等於"DEFAULT_PRODUCER"
throw new MQClientException("producerGroup can not equal " + MixAll.DEFAULT_PRODUCER_GROUP + ", please specify another one.",
null);
}
}
// Validators#checkGroup
public static void checkGroup(String group) throws MQClientException {
if (UtilAll.isBlank(group)) {// 不能爲空
throw new MQClientException("the specified group is blank", null);
}
if (!regularExpressionMatcher(group, PATTERN)) {
throw new MQClientException(String.format(
"the specified group[%s] contains illegal characters, allowing only %s", group,
VALID_PATTERN_STR), null);
}
if (group.length() > CHARACTER_MAX_LENGTH) {// 長度不能大於255
throw new MQClientException("the specified group is longer than group max length 255.", null);
}
}
1.2 getAndCreateMQClientInstance:獲取MQClientInstance。
//MQClientManager#getAndCreateMQClientInstance
public MQClientInstance getAndCreateMQClientInstance(final ClientConfig clientConfig, RPCHook rpcHook) {
String clientId = clientConfig.buildMQClientId();// 構建該Producer的ClientID,等於IP地址@instanceName
MQClientInstance instance = this.factoryTable.get(clientId);
if (null == instance) {// 如果當前客戶端不在mq客戶端實例集合中,則創建一個實例並加入
instance =
new MQClientInstance(clientConfig.cloneClientConfig(),
this.factoryIndexGenerator.getAndIncrement(), clientId, rpcHook);
MQClientInstance prev = this.factoryTable.putIfAbsent(clientId, instance);
if (prev != null) {// 說明一個IP客戶端下面的應用,只有在啓動多個進程的情況下才會創建多個MQClientInstance對象
instance = prev;
log.warn("Returned Previous MQClientInstance for clientId:[{}]", clientId);
} else {
log.info("Created new MQClientInstance for clientId:[{}]", clientId);
}
}
return instance;
}
1.3 registerProducer:註冊Producer。
// MQClientInstance#registerProducer
public boolean registerProducer(final String group, final DefaultMQProducerImpl producer) {
if (null == group || null == producer) {
return false;
}
MQProducerInner prev = this.producerTable.putIfAbsent(group, producer);// 如果沒有添加過,就往producerTable中加入當前的Producer
if (prev != null) {
log.warn("the producer group[{}] exist already.", group);
return false;
}
return true;
}
1.4 MQClientInstance#start 啓動mQClientFactory。
// DefaultMQProducerImpl#start(true)
if (startFactory) {
mQClientFactory.start();
}
// MQClientInstance#start
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();// 獲取nameService地址
}
// Start request-response channel
this.mQClientAPIImpl.start();// 對象負責底層消息通信,獲取nameService地址
// Start various schedule tasks
this.startScheduledTask();// 啓動各種定時任務
// Start pull service
this.pullMessageService.start();// 啓動拉取消息服務
// Start rebalance service
this.rebalanceService.start();// 啓動消費端負載均衡服務
// Start push service
this.defaultMQProducer.getDefaultMQProducerImpl().start(false);// 再次調用DefaultMQProducerImpl.start(),注意傳參爲false。此時ServiceState還是 START_FAILED 只調用了一次心跳服務 this.mQClientFactory.sendHeartbeatToAllBrokerWithLock()
log.info("the client factory [{}] start OK", this.clientId);
this.serviceState = ServiceState.RUNNING;// 改變serviceState狀態爲 RUNNING 啓動狀態
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;
}
}
}
1.4.1 MQClientAPIImpl#start 負責底層消息通信,啓動客戶端對象。
// MQClientAPIImpl#start
public void start() {
this.remotingClient.start();// RemotingClient是RocketMQ封裝了Netty網絡通信的客戶端
}
1.4.2 MQClientInstance#startScheduledTask 啓動各種定時任務。
// MQClientInstance#startScheduledTask
private void startScheduledTask() {
if (null == this.clientConfig.getNamesrvAddr()) {
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
MQClientInstance.this.mQClientAPIImpl.fetchNameServerAddr();// 更新NameServer地址
} 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();// 從nameService更新Topic路由信息
} 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();// 清理掛掉的broker
MQClientInstance.this.sendHeartbeatToAllBrokerWithLock();// 向broker發送心跳信息
} 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();// 持久化consumerOffset,保存消費者的Offset
} 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();// 調整消費線程池
} catch (Exception e) {
log.error("ScheduledTask adjustThreadPool exception", e);
}
}
}, 1, 1, TimeUnit.MINUTES);
}
1.5 MQClientInstance#sendHeartbeatToAllBrokerWithLock 向所有的Broker發送心跳信息。
// MQClientInstance#sendHeartbeatToAllBrokerWithLock
public void sendHeartbeatToAllBrokerWithLock() {
if (this.lockHeartbeat.tryLock()) {
try {
this.sendHeartbeatToAllBroker();// 向所有在MQClientInstance.brokerAddrTable列表中的Broker發送心跳消息
this.uploadFilterClassSource();// 向Filter過濾服務器發送REGISTER_MESSAGE_FILTER_CLASS請求碼,更新過濾服務器中的Filterclass文件
} catch (final Exception e) {
log.error("sendHeartbeatToAllBroker exception", e);
} finally {
this.lockHeartbeat.unlock();
}
} else {
log.warn("lock heartBeat, but failed.");
}
}
上面就是RocketMQ中Producer的啓動過程,上面分析了主要的幾處地方,如果想了解啓動過程中的詳細代碼,可以從Github上面clone代碼到本地,試着調試和分析。附上地址:4.2.0 release。