What is the difference between redis and simple map?

The difference between cache

##Cache is divided into local cache and distributed cache. (Recommended learning:

Redis video tutorial)

Take java as an example, using the built-in map or guava to implement local caching. The main features are lightweight and fast. , the life cycle ends with the destruction of the jvm, and in the case of multiple instances, each instance needs to save its own cache, and the cache is not consistent.

Using redis or memcached is called distributed cache. In the case of multiple instances, each instance shares a cache of data, and the cache is consistent. The disadvantage is that the redis or memcached service needs to be kept highly available, and the entire program architecture is relatively complex.

Of course, if you only save a small amount of data as a cache and there is no need for persistence, you can use Map as a cache.

What is the difference between redis and simple map:

1.

Redis can use dozens of G memory for caching, but Map cannot, and the general JVM only Dividing the data into several G is enough.

2.

Redis’ cache can be persisted. Map is a memory object, and the data will be gone as soon as the program is restarted.

3.

Redis can implement distributed caching. Map can only exist in the program that created it.

4.

Redis can handle millions of concurrency per second and is a professional cache service, Map is just an ordinary object

5,

Redis cache has an expiration mechanism, Map itself does not have this function

6,

Redis has a rich API, Map is too simple

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