layout	title	folder	permalink	categories	tags
pattern	Async Method Invocation	async-method-invocation	/patterns/async-method-invocation/	Concurrency	Reactive

Intent

Asynchronous method invocation is pattern where the calling thread is not blocked while waiting results of tasks. The pattern provides parallel processing of multiple independent tasks and retrieving the results via callbacks or waiting until everything is done.

Class diagram

Applicability

Use async method invocation pattern when

• you have multiple independent tasks that can run in parallel
• you need to improve the performance of a group of sequential tasks
• you have limited amount of processing capacity or long running tasks and the caller should not wait the tasks to be ready

Real world examples

• FutureTask, CompletableFuture and ExecutorService (Java)
• Task-based Asynchronous Pattern (.NET)