Shulou(Shulou.com)05/31 Report--

This article will explain in detail what are the common problems about RocketMQ. Xiaobian thinks it is quite practical, so share it with you for reference. I hope you can gain something after reading this article.

Q: Does RocketMQ have an open API documentation?

A: API documentation is not provided for the time being. The interface uses the example code in the source code.

Q: Can RocketMQ only be deployed on Linux?

A:RocketMQ is written in JAVA and can run on any platform with JRE installed.

Q: Does RocketMQ have to run in JDK64-bit environments?

A: Yes, it must run on an operating system with JRE64-bit installed.

Q: What is the role of nameserver in RocketMQ?

A:nameserver is not used to store data, it is used to provide service discovery functionality, similar to JNDI.

Q: Does broker support distributed deployment?

A: All RocketMQ nodes support deployment by deployment, and distributed deployment of brokers only needs to start brokers on different machines.

Q: Does RocketMQ-3.0.2 support master-slave deployment of brokers?

A: Not currently supported, the development team is testing this feature.

Q: What is the relationship between MetaQ and RocketMQ?

A: MetaQ 3.0 renamed RocketMQ.

Q: Does RocketMQ support standard JMS?

A: Support JMS client API, reference: github.com/RocketMQ-Community/rocketmq-jmsclie

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9. Q: Exception in thread "main" java.lang.NoClassDefFoundError: com/alibaba/rocketmq/broker/BrokerStartup?

A: The source directory bin is not able to start.

10. Q: There is something like admin in tools. Is this a program that monitors the status of mq?

A: Yes, it contains the monitoring interface for managing mq.

11. Q: The recommended configuration on the website is too high. Can you reduce the hardware configuration?

A: Yes, the data on the web page is recommended according to Taobao's business, and the ordinary configuration can run.

Q: Caused by: com.alibaba.rocketmq.client.exception.MQBrokerException: CODE: SERVICE_NOT_AVAILABLE DESC: service not available now.

A: The server disk is full.

Q: Does RocketMQ support Consumer to reconsume messages from a specified time?

A: Support backtracking according to time, precision millisecond, see MQHelper class. 3.0.4 version

Q: How do I set the namerserver address?

A: You can set system properties or set environment variables through java -D, where setting system properties takes precedence over setting environment variables.

Q: Is it good to build a web server and specify the nameserver address?

A: name server can be hot upgraded, you can put a static file in the web server, which is the name server address.

Q:RocketMQ Under what circumstances will msgId appear duplicate?

A: It won't be repeated unless the server's data is wiped clean and then restarted. msgId = Server IP port number + CommitLogOffset.

17, offset save location?

A: For cluster consumption, offset is stored in broker, for broadcast consumption, offset is stored locally by consumer itself.

Q: Can namesrv and broker be closed after startup?

A: mqshutdown broker。

Q: Can data be shared between different versions of RocketMQ?

A: Yes.

20. Q: RocketMQ download address

A: https://github.com/alibaba/RocketMQ or http://git.oschina.net/vintagewang/RocketMQ

Q: How do I delete messages?

A: Using delete topic tool, only topic can be deleted. Messages will not be deleted. When the message expires (the message storage time exceeds and the data volume exceeds 1G), it will be deleted automatically. View ConsumFromWhere method.

22. Q: Router sends message to broker, because broker failed to swipe disk or broker commit file is switching failure, rocketmq will not retry sending or rewriting?

A: Return to client, determined by application, see sendresult.

About "RocketMQ common questions what" this article is shared here, I hope the above content can have some help to everyone, so that you can learn more knowledge, if you think the article is good, please share it to let more people see.

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