Scalability

Concurrency can help us achieve scalability by allowing us to scale out (scale horizontally) rather than scale up (scale vertically).

• Scaling vertically means buying more RAM or a faster processor to get only marginal improvements, and vertical scaling stops once you have already bought the fastest system.
• But we can scale horizontally by distributing the work across multiple machines.

Concurrency can be used to decouple the system. If only one service needs to scale, that can be done easily in a decoupled system rather than to scale everything on a tightly coupled system.