ants

Ants is a Go library that manages a pool of goroutines. A goroutine is Go's lightweight unit of concurrent execution, similar to a thread in other languages, but much cheaper to create. The problem ants solves is that when a program spawns a very large number of goroutines all at once, memory and CPU usage can spiral out of control. Ants provides a pool with a fixed capacity, recycling workers rather than creating new ones for every task.

The library lets you set a maximum number of goroutines that can run at any given time. When you submit a task and the pool is full, the library either queues the task or rejects it immediately, depending on how you configure it. Once a goroutine finishes its task, it goes back into the pool ready to handle the next one. The pool also automatically cleans up goroutines that have been idle too long, keeping memory usage tidy.

Key capabilities listed in the README include submitting tasks, checking how many goroutines are currently running, changing the pool's capacity while the program is running, releasing the pool entirely, and rebooting it after release. If a goroutine panics (crashes unexpectedly), ants catches the panic so the whole program does not go down with it.

There is also an option to pre-allocate memory for the goroutine queue up front. This is useful when you know you will have a very large pool and want to avoid the overhead of repeatedly allocating memory as the queue grows.

Ants works with Go version 1.19 or later and is installed via the standard Go module system. The README includes diagrams illustrating how tasks flow through the pool, and points to additional articles explaining the concepts in more depth.