GopherCon 2018: Kavya Joshi - The Scheduler Saga

he Go scheduler is the behind-the-scenes magical machine that powers Go programs. It efficiently runs goroutines, and also coordinates network IO and memory management.

Kavya’s talk will explore the inner workings of the scheduler machinery. She will delve into the M:N multiplexing of goroutines on system threads, and the mechanisms to schedule, unschedule, and rebalance goroutines. Kavya will also touch upon how the scheduler supports the netpoller and the memory management systems for goroutine stack resizing and heap garbage collection. Finally, she will evaluate the effectiveness and performance of the scheduler.

[andrewlaw]

This really is a great talk. I spent most of the 90s working with task schedulers, and have recently been playing with Go. I'd never seen any explanation of how Go does scheduling, but this talk makes things crystal clear, and maps nicely onto my experience. Kavya clearly knows her stuff, and tries to keep things interesting by changing intonation and using a little stagecraft, rather than letting viewers drift off to sleep. Nice work!

[AmarjeetAnandsingh]

Absolutely amazing presentation. So organized... Thanks kavya for such a great content

[arhyth]

great presenter. i love her older go channels talk.

[blank]

Great talk and explanation, I would definitely watch this again to get a better grasp, thanks Kavya for this awesome talk.

[sbef]

I've been stuck looking to improve an M:N scheduler for my OS/language... found this video and it answers a TON of design and performance questions I had. (Work stealing run queues were the keyword I was looking for) Excellent talk, thanks a bunch!

[varshathkumarterli]

Not sure about you guys, But I'm a beginner and had to rewatch this presentation few times to understand it to the depth. Honestly the content is awesome.

[aseemsavio]

Amazing presentation! I was linked to this from Gophers Slack. I'm grateful for the guy who did that!

[nowarm]

this is so awesome and easy to understand. Thank you for sharing!

[jeffliang]

Amazing and well organized presentation! 👍

[maheshkottapalli]

Thank you a ton. Awesome presentation.

[ishnmu]

Wow! Clean Presentation and Nicely explained. Thanks Kavya

[robgreen]

Excellent content and presentation, thank you.

[wodeqiangne]

nice presentation!personally i love her voice

[alihussainkhan]

Thanks for such an informative content ! Worth saving hours of googling 😀
Since we can create new threads for the goroutines waiting in the local runQ for threads which are blocked on a long running goroutine, as long as the number of goroutine running threads is <= the threshold limit.
If the scheduler does that and in future the blocked threads get unblocked and starts picking goroutines from runQ, then the total number of goroutine running threads will be greater than the limit. Will the scheduler destroy those extra threads then after shifting their runQ elements ?

[cadenzah]

25:25 nice summary, better watch this few times more

[jmcguckin]

What about performing work stealing first from cores located on the same die so as to minimize cache misses…

[richardyang]

On 24:22, what if the T1 wake up? there will be 3 threads, which beyond the limitation of CPU cores?

[ovndfbs]

Nice talk but i still don't know how can you have 200k go routines, with this structure.

[andreypanin]

Damn, she is trying so hard to sound mean!