Distributed Lock Design and Implementation

How do you design distributed locks?

Background

In distributed systems, multiple nodes may concurrently access shared resources, requiring mutual exclusion.

Solution

Redis-based Implementation

Use atomic SET key value NX PX ttl to acquire lock. Use UUID as value to prevent accidental deletion. Use Lua Script for atomic unlock.

ZooKeeper-based Implementation

Use temporary sequential nodes. The client that holds the smallest node owns the lock. Nodes are auto-released when client disconnects.

Redlock Algorithm

Request locks from multiple Redis instances. Lock is acquired only when majority succeeds, improving fault tolerance.

Key Considerations

• Lock TTL must exceed business execution time
• Implement watchdog for automatic lease renewal
• Prevent deadlocks if lock holder crashes