[dullgiulio]

There is no watcher: threads get parked by the kernel as "not runnable" while they perform the I/O operation.

When the operation is finished, then they become runnable again so the kernel scheduler runs them--that is, it runs the code that comes after the I/O operation.

This code (from libuv) notifies the requester that the operation is complete.

[bogomipz]

Thanks. So is the libuv package implemented as two distinct components then consisting of:

1) The main event loop thread.

2) a thread pool of "workers" which make the actual I/O request and sleep while waiting for the I/O. Then when a "worker" thread is set to runnable again by the kernel(because it's I/O request has been completed)notifies the main event loop thread via a signal?

Is that correct?

[dullgiulio]

That's correct, except the notification back is probably via some queue (think of futures or Go channels) rather than signals.

[bogomipz]

I see that makes sense. Cheers.