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0 pointsbogomipz8y ago0 comments

I'm not familiar with libuv but is there a dedicated "watcher" thread in a thread pool that the kernel wakes up when when the disk driver has completed that I/O that it was sleeping on? If so is there a dedicated "watcher" thread for each non-blocking I/O request handled by libuv?

0 comments

dullgiulio8y ago

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.

bogomipzOP8y ago

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?

dullgiulio8y ago

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

1 more reply

steveklabnik8y ago

I’m not familiar at that level.

j / k navigate · click thread line to collapse

0 comments

dullgiulio8y ago

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.

bogomipzOP8y ago

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

1) The main event loop thread.

Is that correct?

dullgiulio8y ago

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

1 more reply

steveklabnik8y ago

I’m not familiar at that level.

j / k navigate · click thread line to collapse