并发中状态的处理

We can’t avoid dealing with state, but we have three options:

• Shared mutability

• Isolated mutability

• Pure immutability

Though we’re used to shared mutability, we should avoid it as much as

possible. Eliminating shared mutable state is the easiest way to avoid synchronization

woes. It takes us far more effort to pick these design approaches

than to pick up a library or an API. It also requires us to step back and

think through how we’d design applications.

We don’t want to compromise performance in order to preserve state. So,

to design with immutability, we’ll need to use modern data structures that

preserve state and at the same time provide great performance.