Part of lp.services.twistedsupport
| Interface | ITaskSource | A source of tasks to do. |
| Interface | ITaskConsumer | A consumer of tasks. |
| Class | PollingTaskSource | A task source that polls to generate tasks. |
| Class | AlreadyRunningError | Raised when we try to start a consumer that's already running. |
| Class | NotRunningError | Raised when we try to run tasks on a consumer before it has started. |
| Class | ParallelLimitedTaskConsumer | A consumer that runs tasks with limited parallelism. |