分布式锁实现协调资源间同步：基于集群Redis（集群分布式redis锁）
Distributed locking, or distributed synchronization, is an important technique for achieving coordination between multiple nodes in a cluster. Using a centralized lock server to coordinate access to shared resources is a typical approach. However, a better approach to distributed locking is to use a distributed system such as a cluster of Redis servers.
Redis, an open source, in-memory data structure store, is a very popular solution for distributed locking among distributed applications. Its scalability, support for replication and automatic failover makes it an ideal choice for applications that need to implement high-performance locks. Redis has built-in native commands for implementing distributed locking in a number of different ways.
One of the more common methods of using Redis for distributed locking is the use of atomic commands such as SETNX, or “SET if Not eXists”. This command can be used to atomically set a key in a Redis instance if it does not already exist. This command allows a single Redis node to act as a distributed locker, as requests coming in to SETNX will be processed as a single operation, thereby providing synchronous coordination. Once the key is set, the node will return an OK status.
The application can then proceed to safely access the shared resource. Once the task is completed, the application will then release the lock by deleting the key from the Redis instance.
Another method of using Redis for distributed locking is through the use of multiple Redis slave nodes, where each node has a unique lock key. When a node is requested to lock a shared resource, that node updates its lock key in the Redis master node to reflect the locked state. If a different node tries to lock the same resource, the master node will ensure that the key is still in the locked state, thus preventing multiple nodes from trying to access the same resource at the same time.
Finally, the Redis cluster can be configured with Sentinel, which provides high availability and disaster recovery capabilities. This ensures that when a Redis node fails, the master node will automatically failover to a different node, thus allowing the distributed locks to remain active and allowing access to the shared resource.
By using Redis in a cluster configuration, distributed locking can be easily implemented with a robust and reliable system. Redis’ built-in commands and replication capabilities provide strong assurance that locks will remain functioning in the event of node failure, thus enabling applications to safely handle access to shared resources.
