源码解析 - rocketmq producer 发送消息

发表于 | 更新于 | 分类于 | 阅读次数：

rocketmq 源码版本: 4.3.1

示例: 同步发送消息

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
/**
 * Send Messages Synchronously
 * Reliable synchronous transmission is used in extensive scenes,
 * such as important notification messages, SMS notification, SMS marketing system, etc..
 */
public class Producer {

    public static void main(String[] args) throws MQClientException, InterruptedException {

        // Instantiate with a producer group name.
        DefaultMQProducer producer = new DefaultMQProducer("producer_group_huohu_rocketmq_test");
        // Specify name server addresses.
        producer.setNamesrvAddr("namesrv_address_1;namesrv_address_2");
        // rocketmq-client 默认开启了 vip 通道，vip 通道端口为 10911-2=10909
        // 若 rocketmq-broker 未开启 vip 通道，则报 connect to <......:10909> failed
        producer.setVipChannelEnabled(false);
        producer.setInstanceName("producer_instance_" + System.currentTimeMillis());

        // Launch the instance.
        producer.start();

        for (int i = 0; i < 16; i++) {
            try {
                // Create a message instance, specifying topic, tag and message body.
                Message msg = new Message("topic_huohu_test_simple_message_syn",
                        "tag_a",
                        "key_order_888888_" + i,
                        ("Hello RocketMQ" + i).getBytes(RemotingHelper.DEFAULT_CHARSET));

                // Call send message to deliver message to one of brokers.
                SendResult sendResult = producer.send(msg);
                System.out.printf("%s%n", sendResult);

                // Send Messages in One-way Mode
                // One-way transmission is used for cases requiring moderate reliability, such as log collection.
                // producer.sendOneway(msg);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        Thread.sleep(1 * 60 * 1000L);

        producer.shutdown();
    }
}

概览

模块交互

Producer 发送消息模块交互图

发送消息

Producer 发送消息时序图

源码解析

DefaultMQProducer

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
public class DefaultMQProducer extends ClientConfig implements MQProducer {

    /**
     * Wrapping internal implementations for virtually all methods presented in this class.
     */
    protected final transient DefaultMQProducerImpl defaultMQProducerImpl;

    // ...

    /**
     * Just for testing or demo program
     */
    private String createTopicKey = MixAll.AUTO_CREATE_TOPIC_KEY_TOPIC;

    /**
     * Number of queues to create per default topic.
     */
    private volatile int defaultTopicQueueNums = 4;

    /**
     * Timeout for sending messages.
     */
    private int sendMsgTimeout = 3000;

    /**
     * Compress message body threshold, namely, message body larger than 4k will be compressed on default.
     */
    private int compressMsgBodyOverHowmuch = 1024 * 4;

    /**
     * Maximum number of retry to perform internally before claiming sending failure in synchronous mode.
     * </p>
     *
     * This may potentially cause message duplication which is up to application developers to resolve.
     */
    private int retryTimesWhenSendFailed = 2;

    /**
     * Maximum number of retry to perform internally before claiming sending failure in asynchronous mode.
     * </p>
     *
     * This may potentially cause message duplication which is up to application developers to resolve.
     */
    private int retryTimesWhenSendAsyncFailed = 2;

    /**
     * Indicate whether to retry another broker on sending failure internally.
     */
    private boolean retryAnotherBrokerWhenNotStoreOK = false;

    /**
     * Maximum allowed message size in bytes.
     */
    private int maxMessageSize = 1024 * 1024 * 4; // 4M

    @Override
    public void start() throws MQClientException {
        this.defaultMQProducerImpl.start();
    }

    @Override
    public void shutdown() {
        this.defaultMQProducerImpl.shutdown();
    }

    @Override
    public SendResult send(
        Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
        return this.defaultMQProducerImpl.send(msg);
    }

    // ...
}

DefaultMQProducerImpl#sendDefaultImpl

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

/**
 * DEFAULT SYNC -------------------------------------------------------
 */
public SendResult send(Message msg) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
    return send(msg, this.defaultMQProducer.getSendMsgTimeout());
}

public SendResult send(Message msg, long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {
    return this.sendDefaultImpl(msg, CommunicationMode.SYNC, null, timeout);
}

private SendResult sendDefaultImpl(
    Message msg,
    final CommunicationMode communicationMode,
    final SendCallback sendCallback,
    final long timeout
) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {

    this.makeSureStateOK();
    Validators.checkMessage(msg, this.defaultMQProducer);

    final long invokeID = random.nextLong();
    long beginTimestampFirst = System.currentTimeMillis();
    long beginTimestampPrev = beginTimestampFirst;
    long endTimestamp = beginTimestampFirst;

    // 获取 Topic 路由信息
    TopicPublishInfo topicPublishInfo = this.tryToFindTopicPublishInfo(msg.getTopic());
    if (topicPublishInfo != null && topicPublishInfo.ok()) {
        boolean callTimeout = false;
        MessageQueue mq = null;
        Exception exception = null;
        SendResult sendResult = null;
        int timesTotal = communicationMode == CommunicationMode.SYNC ? 1 + this.defaultMQProducer.getRetryTimesWhenSendFailed() : 1;// SYNC 失败会重试 (1 + 2)
        int times = 0;
        String[] brokersSent = new String[timesTotal];

        // 循环发送消息
        for (; times < timesTotal; times++) {
            String lastBrokerName = null == mq ? null : mq.getBrokerName();
            MessageQueue mqSelected = this.selectOneMessageQueue(topicPublishInfo, lastBrokerName);// 选择消息要发送到的队列
            if (mqSelected != null) {
                mq = mqSelected;
                brokersSent[times] = mq.getBrokerName();
                try {
                    beginTimestampPrev = System.currentTimeMillis();
                    long costTime = beginTimestampPrev - beginTimestampFirst;
                    if (timeout < costTime) {
                        callTimeout = true;
                        break;
                    }

                    // 发送消息核心方法
                    sendResult = this.sendKernelImpl(msg, mq, communicationMode, sendCallback, topicPublishInfo, timeout - costTime);
                    endTimestamp = System.currentTimeMillis();
                    // 更新Broker可用性信息
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, false);
                    switch (communicationMode) {
                        case ASYNC:
                            return null;
                        case ONEWAY:
                            return null;
                        case SYNC:
                            if (sendResult.getSendStatus() != SendStatus.SEND_OK) {
                                if (this.defaultMQProducer.isRetryAnotherBrokerWhenNotStoreOK()) {
                                    continue;// SYNC 发送消息成功但存储有问题 && 配置存储异常时重新发送开关 -> 重试
                                }
                            }

                            return sendResult;
                        default:
                            break;
                    }
                } catch (RemotingException e) {
                    endTimestamp = System.currentTimeMillis();
                    // 异常, 更新Broker可用性信息
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                    log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());
                    exception = e;
                    continue;
                } catch (MQClientException e) {
                    endTimestamp = System.currentTimeMillis();
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                    log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());
                    exception = e;
                    continue;
                } catch (MQBrokerException e) {
                    endTimestamp = System.currentTimeMillis();
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, true);
                    log.warn(String.format("sendKernelImpl exception, resend at once, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());
                    exception = e;
                    switch (e.getResponseCode()) {
                        case ResponseCode.TOPIC_NOT_EXIST:
                        case ResponseCode.SERVICE_NOT_AVAILABLE:
                        case ResponseCode.SYSTEM_ERROR:
                        case ResponseCode.NO_PERMISSION:
                        case ResponseCode.NO_BUYER_ID:
                        case ResponseCode.NOT_IN_CURRENT_UNIT:
                            continue;
                        default:
                            if (sendResult != null) {
                                return sendResult;
                            }

                            throw e;
                    }
                } catch (InterruptedException e) {
                    endTimestamp = System.currentTimeMillis();
                    this.updateFaultItem(mq.getBrokerName(), endTimestamp - beginTimestampPrev, false);
                    log.warn(String.format("sendKernelImpl exception, throw exception, InvokeID: %s, RT: %sms, Broker: %s", invokeID, endTimestamp - beginTimestampPrev, mq), e);
                    log.warn(msg.toString());

                    log.warn("sendKernelImpl exception", e);
                    log.warn(msg.toString());
                    throw e;
                }
            } else {
                break;
            }
        }

        if (sendResult != null) {
            return sendResult;
        }

        String info = String.format("Send [%d] times, still failed, cost [%d]ms, Topic: %s, BrokersSent: %s",
            times,
            System.currentTimeMillis() - beginTimestampFirst,
            msg.getTopic(),
            Arrays.toString(brokersSent));

        info += FAQUrl.suggestTodo(FAQUrl.SEND_MSG_FAILED);

        MQClientException mqClientException = new MQClientException(info, exception);
        if (callTimeout) {
            throw new RemotingTooMuchRequestException("sendDefaultImpl call timeout");
        }

        if (exception instanceof MQBrokerException) {
            mqClientException.setResponseCode(((MQBrokerException) exception).getResponseCode());
        } else if (exception instanceof RemotingConnectException) {
            mqClientException.setResponseCode(ClientErrorCode.CONNECT_BROKER_EXCEPTION);
        } else if (exception instanceof RemotingTimeoutException) {
            mqClientException.setResponseCode(ClientErrorCode.ACCESS_BROKER_TIMEOUT);
        } else if (exception instanceof MQClientException) {
            mqClientException.setResponseCode(ClientErrorCode.BROKER_NOT_EXIST_EXCEPTION);
        }

        throw mqClientException;
    }

    // No name server address
    List<String> nsList = this.getmQClientFactory().getMQClientAPIImpl().getNameServerAddressList();
    if (null == nsList || nsList.isEmpty()) {
        throw new MQClientException(
            "No name server address, please set it." + FAQUrl.suggestTodo(FAQUrl.NAME_SERVER_ADDR_NOT_EXIST_URL), null).setResponseCode(ClientErrorCode.NO_NAME_SERVER_EXCEPTION);
    }

    // No route info of this topic
    throw new MQClientException("No route info of this topic, " + msg.getTopic() + FAQUrl.suggestTodo(FAQUrl.NO_TOPIC_ROUTE_INFO),
        null).setResponseCode(ClientErrorCode.NOT_FOUND_TOPIC_EXCEPTION);
}

DefaultMQProducerImpl#tryToFindTopicPublishInfo(topic)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
private TopicPublishInfo tryToFindTopicPublishInfo(final String topic) {
    // 缓存中获取 Topic 发布信息
    TopicPublishInfo topicPublishInfo = this.topicPublishInfoTable.get(topic);
    // 当无可用的 Topic 发布信息时，从 namesrv 获取
    if (null == topicPublishInfo || !topicPublishInfo.ok()) {
        this.topicPublishInfoTable.putIfAbsent(topic, new TopicPublishInfo());
        this.mQClientFactory.updateTopicRouteInfoFromNameServer(topic);
        topicPublishInfo = this.topicPublishInfoTable.get(topic);
    }

    // 若获取的 Topic 发布信息可用，则返回
    if (topicPublishInfo.isHaveTopicRouterInfo() || topicPublishInfo.ok()) {
        return topicPublishInfo;
    } else {// 当从 namesrv 无法获取时，使用 {@link DefaultMQProducer#createTopicKey} 对应的 Topic发布信息 -> 目的是当 Broker 开启自动创建 Topic开关时，Broker 接收到消息后自动创建Topic
        this.mQClientFactory.updateTopicRouteInfoFromNameServer(topic, true, this.defaultMQProducer);
        topicPublishInfo = this.topicPublishInfoTable.get(topic);
        return topicPublishInfo;
    }
}

DefaultMQProducerImpl#sendKernelImpl

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
private SendResult sendKernelImpl(final Message msg,
                                  final MessageQueue mq,
                                  final CommunicationMode communicationMode,
                                  final SendCallback sendCallback,
                                  final TopicPublishInfo topicPublishInfo,
                                  final long timeout) throws MQClientException, RemotingException, MQBrokerException, InterruptedException {

    long beginStartTime = System.currentTimeMillis();

    // 获取 broker 地址
    String brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
    if (null == brokerAddr) {
        tryToFindTopicPublishInfo(mq.getTopic());
        brokerAddr = this.mQClientFactory.findBrokerAddressInPublish(mq.getBrokerName());
    }

    SendMessageContext context = null;
    if (brokerAddr != null) {

        // 是否使用 broker vip 通道: broker会开启两个端口对外服务
        brokerAddr = MixAll.brokerVIPChannel(this.defaultMQProducer.isSendMessageWithVIPChannel(), brokerAddr);

        byte[] prevBody = msg.getBody();
        try {
            //for MessageBatch,ID has been set in the generating process
            if (!(msg instanceof MessageBatch)) {
                MessageClientIDSetter.setUniqID(msg);
            }

            // 消息压缩
            int sysFlag = 0;
            boolean msgBodyCompressed = false;
            if (this.tryToCompressMessage(msg)) {
                sysFlag |= MessageSysFlag.COMPRESSED_FLAG;
                msgBodyCompressed = true;
            }

            // 事务消息
            final String tranMsg = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
            if (tranMsg != null && Boolean.parseBoolean(tranMsg)) {
                sysFlag |= MessageSysFlag.TRANSACTION_PREPARED_TYPE;
            }

            // hook：发送消息校验
            if (hasCheckForbiddenHook()) {
                CheckForbiddenContext checkForbiddenContext = new CheckForbiddenContext();
                checkForbiddenContext.setNameSrvAddr(this.defaultMQProducer.getNamesrvAddr());
                checkForbiddenContext.setGroup(this.defaultMQProducer.getProducerGroup());
                checkForbiddenContext.setCommunicationMode(communicationMode);
                checkForbiddenContext.setBrokerAddr(brokerAddr);
                checkForbiddenContext.setMessage(msg);
                checkForbiddenContext.setMq(mq);
                checkForbiddenContext.setUnitMode(this.isUnitMode());
                this.executeCheckForbiddenHook(checkForbiddenContext);
            }

            // hook：发送消息前逻辑
            if (this.hasSendMessageHook()) {
                context = new SendMessageContext();
                context.setProducer(this);
                context.setProducerGroup(this.defaultMQProducer.getProducerGroup());
                context.setCommunicationMode(communicationMode);
                context.setBornHost(this.defaultMQProducer.getClientIP());
                context.setBrokerAddr(brokerAddr);
                context.setMessage(msg);
                context.setMq(mq);
                String isTrans = msg.getProperty(MessageConst.PROPERTY_TRANSACTION_PREPARED);
                if (isTrans != null && isTrans.equals("true")) {
                    context.setMsgType(MessageType.Trans_Msg_Half);
                }

                if (msg.getProperty("__STARTDELIVERTIME") != null || msg.getProperty(MessageConst.PROPERTY_DELAY_TIME_LEVEL) != null) {
                    context.setMsgType(MessageType.Delay_Msg);
                }
                this.executeSendMessageHookBefore(context);
            }

            // 构建发送消息请求头
            SendMessageRequestHeader requestHeader = new SendMessageRequestHeader();
            requestHeader.setProducerGroup(this.defaultMQProducer.getProducerGroup());
            requestHeader.setTopic(msg.getTopic());
            requestHeader.setDefaultTopic(this.defaultMQProducer.getCreateTopicKey());
            requestHeader.setDefaultTopicQueueNums(this.defaultMQProducer.getDefaultTopicQueueNums());
            requestHeader.setQueueId(mq.getQueueId());
            requestHeader.setSysFlag(sysFlag);
            requestHeader.setBornTimestamp(System.currentTimeMillis());
            requestHeader.setFlag(msg.getFlag());
            requestHeader.setProperties(MessageDecoder.messageProperties2String(msg.getProperties()));
            requestHeader.setReconsumeTimes(0);
            requestHeader.setUnitMode(this.isUnitMode());
            requestHeader.setBatch(msg instanceof MessageBatch);
            if (requestHeader.getTopic().startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX)) {
                String reconsumeTimes = MessageAccessor.getReconsumeTime(msg);
                if (reconsumeTimes != null) {
                    requestHeader.setReconsumeTimes(Integer.valueOf(reconsumeTimes));
                    MessageAccessor.clearProperty(msg, MessageConst.PROPERTY_RECONSUME_TIME);
                }

                String maxReconsumeTimes = MessageAccessor.getMaxReconsumeTimes(msg);
                if (maxReconsumeTimes != null) {
                    requestHeader.setMaxReconsumeTimes(Integer.valueOf(maxReconsumeTimes));
                    MessageAccessor.clearProperty(msg, MessageConst.PROPERTY_MAX_RECONSUME_TIMES);
                }
            }

            // 发送消息
            SendResult sendResult = null;
            switch (communicationMode) {
                case ASYNC:
                    Message tmpMessage = msg;
                    if (msgBodyCompressed) {
                        //If msg body was compressed, msgbody should be reset using prevBody.
                        //Clone new message using commpressed message body and recover origin massage.
                        //Fix bug:https://github.com/apache/rocketmq-externals/issues/66
                        tmpMessage = MessageAccessor.cloneMessage(msg);
                        msg.setBody(prevBody);
                    }
                    long costTimeAsync = System.currentTimeMillis() - beginStartTime;
                    if (timeout < costTimeAsync) {
                        throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
                    }
                    sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
                        brokerAddr,
                        mq.getBrokerName(),
                        tmpMessage,
                        requestHeader,
                        timeout - costTimeAsync,
                        communicationMode,
                        sendCallback,
                        topicPublishInfo,
                        this.mQClientFactory,
                        this.defaultMQProducer.getRetryTimesWhenSendAsyncFailed(),
                        context,
                        this);
                    break;
                case ONEWAY:
                case SYNC:
                    long costTimeSync = System.currentTimeMillis() - beginStartTime;
                    if (timeout < costTimeSync) {
                        throw new RemotingTooMuchRequestException("sendKernelImpl call timeout");
                    }
                    sendResult = this.mQClientFactory.getMQClientAPIImpl().sendMessage(
                        brokerAddr,
                        mq.getBrokerName(),
                        msg,
                        requestHeader,
                        timeout - costTimeSync,
                        communicationMode,
                        context,
                        this);
                    break;
                default:
                    assert false;
                    break;
            }

            // hook：发送消息后逻辑
            if (this.hasSendMessageHook()) {
                context.setSendResult(sendResult);
                this.executeSendMessageHookAfter(context);
            }

            return sendResult;
        } catch (RemotingException e) {
            if (this.hasSendMessageHook()) {
                context.setException(e);
                this.executeSendMessageHookAfter(context);
            }
            throw e;
        } catch (MQBrokerException e) {
            if (this.hasSendMessageHook()) {
                context.setException(e);
                this.executeSendMessageHookAfter(context);
            }
            throw e;
        } catch (InterruptedException e) {
            if (this.hasSendMessageHook()) {
                context.setException(e);
                this.executeSendMessageHookAfter(context);
            }
            throw e;
        } finally {
            msg.setBody(prevBody);
        }
    }

    // MQClientException: broker not exist
    throw new MQClientException("The broker[" + mq.getBrokerName() + "] not exist", null);
}

MQClientAPIImpl#sendMessage

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

private final RemotingClient remotingClient;
this.remotingClient = new NettyRemotingClient(nettyClientConfig, null);

case ONEWAY:
    this.remotingClient.invokeOneway(addr, request, timeoutMillis);
    return null;
case ASYNC:
    this.remotingClient.invokeAsync(addr, request, timeoutMillis, new InvokeCallback() {
        // ...
    });
    return null;
case SYNC:
    RemotingCommand response = this.remotingClient.invokeSync(addr, request, timeoutMillis);
    return response;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
DefaultMQPullConsumerImpl
DefaultMQPushConsumerImpl

    public synchronized void start() 

                    this.mQClientFactory = MQClientManager.getInstance().getAndCreateMQClientInstance(this.defaultMQPullConsumer, this.rpcHook);

DefaultMQProducerImpl
    public void start(final boolean startFactory) 
                    this.mQClientFactory = MQClientManager.getInstance().getAndCreateMQClientInstance(this.defaultMQProducer, rpcHook);


    public MQClientInstance getAndCreateMQClientInstance(final ClientConfig clientConfig, RPCHook rpcHook) {
        String clientId = clientConfig.buildMQClientId();
        MQClientInstance instance = this.factoryTable.get(clientId);
        if (null == instance) {
            instance =
                new MQClientInstance(clientConfig.cloneClientConfig(),
                    this.factoryIndexGenerator.getAndIncrement(), clientId, rpcHook);
            MQClientInstance prev = this.factoryTable.putIfAbsent(clientId, instance);
            if (prev != null) {
                instance = prev;
                log.warn("Returned Previous MQClientInstance for clientId:[{}]", clientId);
            } else {
                log.info("Created new MQClientInstance for clientId:[{}]", clientId);
            }
        }

        return instance;
    }

   public MQClientInstance(ClientConfig clientConfig, int instanceIndex, String clientId, RPCHook rpcHook) {
        this.clientConfig = clientConfig;
        this.instanceIndex = instanceIndex;
        this.nettyClientConfig = new NettyClientConfig();
        this.nettyClientConfig.setClientCallbackExecutorThreads(clientConfig.getClientCallbackExecutorThreads());
        this.nettyClientConfig.setUseTLS(clientConfig.isUseTLS());
        this.clientRemotingProcessor = new ClientRemotingProcessor(this);
        this.mQClientAPIImpl = new MQClientAPIImpl(this.nettyClientConfig, this.clientRemotingProcessor, rpcHook, clientConfig);

        if (this.clientConfig.getNamesrvAddr() != null) {
            this.mQClientAPIImpl.updateNameServerAddressList(this.clientConfig.getNamesrvAddr());
            log.info("user specified name server address: {}", this.clientConfig.getNamesrvAddr());
        }

        // ...
    }

参考

本文参考了互联网上大家的分享，就不一一列举，在此一并谢过。
也希望本文，能对大家有所帮助，若有错误，还请谅解、指正。