Distributed locks and three implementation methods

I. What is a distributed lock

Distributed locks are a way to control synchronous access to shared resources between distributed systems. In order to prevent multiple processes in a distributed system from interfering with each other, it is necessary to coordinate these processes on different machines.

If one or a group of resources are shared between different systems or different hosts of the same system, when accessing these resources, mutual exclusion is often required to prevent mutual interference and ensure consistency. At this time, it is necessary toUse distributed locks.

Distributed locks should have the following conditions:

• In a distributed system environment, a method can only be executed by one thread of one machine at a time;
• Highly available acquire lock and release lock;
• High-performance lock acquisition and release;
• It is reentrant;
• Have a lock failure mechanism to prevent deadlock;
• It has the feature of non-blocking lock, that is, if the lock is not acquired, it will directly return the failure to acquire the lock.

Second, the way to realize distributed lock

Implementation	Link
Distributed lock based on database	Click to view
Distributed lock based on cache (Redis)	Click to view
The principle of distributed lock based on Zookeeper	Click to view

In terms of ease of understanding (from low to high)

Database > Cache > Zookeeper

From an implementation complexity perspective (low to high)

Zookeeper >= cache > database

From a performance perspective (high to low)

Cache> Zookeeper >= Database

From a reliability perspective (high to low)

Zookeeper > Cache > Database