SequencedExecutor

[Adeynack]

Use cases

• Limit the number of parallel tasks of a similar nature that are executed at the same time to 1.
• Ensure mutually exclusive "lock" over a mutable resource without blocking
  • Done by configuring this Executor with only 1 parallel task.
  • Example: Protect a mutable state inside of a service

Why not ...

... use Executors.newSingleThreadExecutor();

Because it creates a new thread. This proposition is an Executor that limits without creating any new thread. The thread pool already exist and we want to use it. In the end, the tasks are dispatched to an existing Executor (which does not have to be a pool, but is the typical use).

Specifications

• Based on an existing executor (composite)