What are the advantages and disadvantages of Kafka, ActiveMQ, RabbitMQ and RocketMQ

When designing the architecture of large-scale systems, it is often necessary to consider the problems of high concurrency / component decoupling / traffic peaking. At this point, the message component must be used. There are three common usage scenarios of message queuing: decoupling, asynchronism (high concurrency), and peak clipping.

Common message components are: Kafka, ActiveMQ, RabbitMQ, RocketMQ. Someone has summarized the comparison between them. I reprinted a netizen's summary:

What are the advantages and disadvantages of Kafka, ActiveMQ, RabbitMQ and RocketMQ?

How much key can be stored in an instance of redis?

Officials say a single case can handle key: 250 million, see link: https://redis.io/topics/faq

What is the maximum size of a key and value in redis?

A key or value with a maximum of 512m