Go (Golang) Semaphore Pattern Tutorial

Semaphores are a synchronization mechanism not new to computer science and present in other programming languages other than Go. With Semaphores we can synchronize access to multiple resources or in the episode we are going to see today, we are rate-limiting or throttling a set of concurrent workers to a pre-defined fixed capacity.
In this episode we are going to look at our we can limit the number of concurrent go routines running by using a buffered channel first and later on a packaged solution developed by the Go team (golang.org/x/sync/semaphore).
Buffered channels are the perfect solution for this problem as they are a tool to communicate safely between concurrent workers in go.
Buffered Channels in Go - tour.golang.or...
Semaphore package - pkg.go.dev/gol...
Source Code (with golang.org/x/sync/semaphore) - play.golang.or...
Source Code (with buffered channel) - play.golang.or...
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[@rikisyahputra3805]

The accent adds so much to the video, love it!

[@DeeptimanPattnaik1991]

Brilliant explanation on semaphore & errgroup with quick Pseudocode. !!!

[@GolangCafe]

Thank you Deeptiman I am glad it was helpful

[@GolangDojo]

I love how you start out the senario from the basics and build toward different solutions and problems (and then again the solutions for them). Question - How do we know if the semaphore has been incremented if the acquire is returning an error? Is there an elegant way to recover it?

[@nicolasparada]

Exactly. I don't get exactly `sync/semaphore` work flow (because the error return) so normally I just stick to buffered channels 🙂 Tho, I use an empty struct instead of bool: `sem := make(chan struct{}, size)` `sem

[@nicolasparada]

I was looking at the internal code now, and the error can happen because a ctx error, or because you tried to acquire more than even the semaphore size. So it's not something you should try and recover.

[@GolangCafe]

Thanks for your comment! The semaphore.Weighted.Acquire will block, just like sending an item into the buffered channel will block. It will return an error if the context is cancelled in the middle of the acquire process (for example if you set a global timeout on the whole operation) - an example on how the context and cancellation events work is covered here kzbin.info/www/bejne/fYrXi6aviZmagdE

[@GolangCafe]

@@nicolasparada Thanks, that's a great suggestion, I was meant to add that into the example, but I fear that most people will just be confused by the empty struct, but that's totally legit! I will try cover it in a new episode

[@a_maxed_out_handle_of_30_chars]

@@nicolasparada thanks for this

[@adicide9070]

thanks for this. that said, for presentation purposes, please use smaller indent and break down long lines. thanks.

[@Gamerultroll]

I really like the way you're teaching. keep doing it bro u are really good!

[@GolangCafe]

Thank you for watching!

[@nicolasparada]

Great video. Awesome techniques we can make use of everyday and improve performance 👍 Goroutines are great, but have them without limits can also affect performance. A semaphore is just perfect in those scenarios 🚦

[@GolangCafe]

Thank you for watching Nicolás!

[@antonyinjila7152]

Awesome tutorial. Feel like a senior Go dev already. @Golang Dojo, you also doing a great job. Bigup to you as well

[@GolangCafe]

Thank you

[@VinayJeurkar]

Nice explanation

[@rabingaire]

Great video as usual

[@blckhwk8024]

Thanks for tutorial, concept easily explained

[@merlin7411]

Sir! Thx u very much!!!!You helps me!!!!

[@n810h]

Love the videos. Hope you start making more!

[@GolangCafe]

Thank you! I hope to start again in a few weeks :)

[@buntysingh7315]

i hope everything is well with you brother long time no vids 😅

[@johnstorm589]

Well done! Great explanation

[@a_maxed_out_handle_of_30_chars]

as usual thank you for the quality content, also are you italian? at 12:51 i noticed italian accent

[@khawarizmyana]

Thanks!

[@vanshajdhar9223]

Why you stopped your content it was gem

[@imteyazraja5989]

Really love the way u explain. Can we have one comple project in golang? What's ur profile / github repo/ any courses? Thanks for everything..loved it.

[@GolangCafe]

Thank you! No courses yet. But we have a repository with open source Golang Cafe golang.cafe/github :) Will do more tutorials soon maybe more project-style based. Thank you!

[@maximpng6466]

Когда вы научитесь хотя бы медленно говорить, это ужасный акцент.

[@GolangCafe]

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