Introduce a,
Apache RocketMQ is a distributed, queued model of messaging middleware with low latency, high performance and reliability, trillion-scale capacity, and flexible scalability. The core component consists of four parts: Name Servers, Brokers, Producer and Consumer. Each of them can scale horizontally without a single failed node.
NameServer: is a nearly stateless node that can be clustered and no information is synchronized between nodes
Broker: The deployment is relatively complex. Brokers are divided into Master and Slave brokers. A Master can correspond to multiple Slavers, but a Slaver can only correspond to one Master. A different BrokerId is defined, with a BrokerId 0 for Master and a non-0 for Slaver. Multiple Master can be deployed. Each Broker establishes long connections to all nodes in the NameServer cluster and periodically registers Topic information to all Nameservers
Producer: Establishes a long connection with a node (randomly selected) in the NameServer cluster, obtains Topic routing information from NameServer regularly, establishes a long connection with the Master that provides Topic services, and sends heartbeat messages to the Master periodically. Produce is stateless and can be clustered
Consumer: Establishes a long-term connection with a node (randomly selected) in the NameServer cluster, obtains Topic routing information from NameServer periodically, establishes a long-term connection with the Master and Slaver that provide Topic services, and periodically sends heartbeat messages to the Master and Slaver. Consumers can subscribe to messages from either Master or Slave, depending on the Broker configuration
Ii. MQ installation and deployment
Download 2.1.
Download the latest version and unpack it
http://rocketmq.apache.org/release_notes
2.2. Modify the configuration
** Modify conf/broker.conf** add the following configuration
BrokerIP1: Configure the IP address of the broker Server so that the Name Server can connect
Change runserver.sh and runbroker.sh (optional)
Because the rocketMQ default startup parameter is very memory intensive, the JAVA_OPT parameter must be modified if the environment does not have this amount of memory
runserver.sh
JAVA_OPT=${JAVA_OPT} -server -Xms256m -Xmx256m -Xmn125m -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=320m
runbroker.sh
JAVA_OPT=${JAVA_OPT} -server -Xms256m -Xmx256m -Xmn125m -XX:MetaspaceSize=128m -XX:MaxMetaspaceSize=320m
2.3. Run Name Server
nohup sh bin/mqnamesrv
Check run log: tail -f ~ / logs/rocketmqlogs/namesrv log
2.4. Run the Broker
nohup sh bin/mqbroker -n localhost:9876 -c conf/broker.conf
Specify the configuration file using the -c parameter
Check run log: tail – f ~ / logs/rocketmqlogs/broker. The log
2.5. Way to stop service
To stop the RocketMQ service, you are advised to run the kill command instead of the kill command in the production environment
sh bin/mqshutdown broker
sh bin/mqshutdown namesrv
Install a visual management interface
download
https://github.com/apache/rocketmq-externals/tree/master/rocketmq-console
compile
mvn clean package -Dmaven.test.skip=true
run
nohup java -jar \
– Drocketmq. Config. NamesrvAddr = 192.168.28.130: \ 9876
-Drocketmq.config.isVIPChannel=false \
Rocketmq – the console – ng – 1.0.0. Jar
access
http://192.168.28.130:8080/
Four, common exception processing
4.1. MQClientException: No route info of this topic, TopicTest1
4.1.1. Exception Description
When the Producer of the client is running and ready to send messages, an exception is thrown as “No route info of this topic”. The possible causes are as follows:
The Broker disallows automatic creation of topics, and users do not create topics manually
The Broker is not properly connected to the Name Server
Producer is not properly connected to the Name Server
4.1.2. Solution
Troubleshooting 1: The Broker forbids automatic Topic creation and the user does not manually create a Topic
To view the broker configuration parameters, run sh bin/ mqbroker-m in the RocketMQ directory
As shown below, autoCreateTopicEnable=true proves that there is no problem
Troubleshoot 2: The Broker is not properly connected to the Name Server
By looking at the broker log tail – f ~ / logs/rocketmqlogs/broker. The log to see if there is any error information
Check 3: Producer is not correctly connected to the Name Server
Check whether the program connects to the Name Server at the correct address
If the security group is configured on a cloud server, check whether port 9876 is developed
See if the firewall is on, and if so, set up a firewall to open port 9876
4.2. RemotingTooMuchRequestException: sendDefaultImpl call a timeout
4.2.1. Exception Description
The following exception is thrown when the Producer of the client is up and ready to send messages
This is usually because the Name Server cannot connect to the Broker
4.2.2. Solution
Check the RocketMQ-Console cluster TAB for the correct broker address
Refer to the steps in installation and deployment to configure the broker address:
Modify the broker.conf configuration to add the brokerIP1 parameter
Start the broker with the -c parameter to specify the configuration file
4.3. Unable to consume/view messages from the dead-letter queue topic
4.3.1. Exception Description
The default perm value of a dead letter queue is 2
4.3.2. Solution
Change the queue’s PERM to 6 on the console
** TOPIC click TOPIC configuration **
Modify the perm
