What are Redis distributed lock patterns and implementations?

Redis distributed locks coordinate access to shared resources across multiple processes or servers, preventing race conditions and ensuring data consistency.\n\n• **Why Use Distributed Locks?**\nPrevent concurrent modifications, ensure atomic operations across services, coordinate resource access, and maintain data integrity in distributed systems.\n\n• **Simple Lock Pattern:**\nUse SET with NX (not exists) and EX (expiration) for atomic lock acquisition with automatic cleanup.\n\nSET lock:resource:123 unique_token NX EX 30\nif result == "OK": lock acquired\n\n• **Safe Lock Release:**\nUse Lua script to ensure only lock owner can release, preventing accidental unlocks by other processes.\n\nlocal token = redis.call("GET", KEYS[1])\nif token == ARGV[1] then\n return redis.call("DEL", KEYS[1])\nend\n\n• **Python Implementation:**\nimport redis\nimport uuid\n\nclass RedisLock:\n def acquire(self):\n token = str(uuid.uuid4())\n result = redis.set(self.key, token, nx=True, ex=30)\n return result is not None\n \n def release(self):\n # Use Lua script for safe release\n\n• **Redlock Algorithm:**\nAcquire locks on majority of Redis instances (3, 5, 7) for higher reliability in multi-master setups.\n\n• **Best Practices:**\nAlways set expiration, use unique tokens, implement retry with backoff, monitor lock contention, and consider lock-free alternatives when possible.