Close waits all jobs to finish and closes the semaphore of global ParallelManager.

Init tries to increase the soft limit of open files and creates new global ParallelManager.

New creates a new parallel.Manager.

NewWaiter creates a new parallel.Waiter.

Run runs global ParallelManager.

Manager is a structure for running tasks in parallel.

Waiter is a structure for waiting and reading error messages created by Manager.

Task is a function type for parallel manager.