nginx - load balancing issues

Question

What are the similarities and differences between nginx/zookeeper load balancing functions?

Answer 1

Zookeeper distributed service framework is a sub-project of Apache Hadoop. It is mainly used to solve some data management problems often encountered in distributed applications, such as: unified naming service, status synchronization service, cluster management, distributed application configuration Item management, etc.

1. zookeeper is a streamlined file system. In this regard, it is somewhat similar to Hadoop, but the file system ZooKeeper manages small files, while Hadoop manages very large files.

2. zookeeper provides a wealth of "components" that can implement many operations that coordinate data structures and protocols. For example: distributed queues, distributed locks, and "leader election" algorithms for a group of peer nodes.

3. zookeeper is highly available and its stability is quite good. Distributed clusters can completely rely on the management of the zookeeper cluster and use 4. zookeeper to avoid the single point of failure problem of the distributed system.

4. zookeeper adopts a loosely coupled interaction model. This is most obvious when zookeeper provides distributed locks. Zookeeper can be used as an appointment mechanism, allowing participating processes to discover and interact with each other without knowing other processes (or networks). The participating parties can even They do not have to exist at the same time, as long as a message is left in zookeeper, after the process ends, another process can also read this information, thereby decoupling the relationship between the nodes.

5. zookeeper provides a shared repository for the cluster, from which the cluster can centrally read and write shared information, avoiding the shared operation programming of each node and easing the difficulty of developing distributed systems.

6. The design of zookeeper adopts the observer design pattern. Zookeeper is mainly responsible for storing and managing the data that everyone cares about, and then accepts the registration of observers. Once the status of these data changes, Zookeeper will be responsible for notifying those already on Zookeeper. Those registered observers react accordingly, thereby achieving a similar Master/Slave management model in the cluster.
   It can be seen that zookeeper is very conducive to the development of distributed systems. It can make distributed systems more robust and efficient.

　Nginx uses reverse proxy technology. The proxy server accepts connection requests on the Internet, then forwards the requests to the server on the internal network, and returns the results obtained from the server to the client requesting the connection on the Internet. This At this time, the proxy server appears as a server to the outside world. Reverse proxy load balancing technology dynamically forwards connection requests from the Internet to multiple servers on the internal network for processing in a reverse proxy manner, thereby achieving the purpose of load balancing. It is a high-performance HTTP and reverse proxy server, as well as an IMAP/POP3/SMTP proxy server. It can be said that Nginx is currently the most widely used HTTP soft load balancer