I’m sorry but your design is not comprehendible by me, and I’ve done lots of TCP based services.
i think you only need to emulate classic TCP processing - a reader thread (Go routine) on each side of the connection using range to read until closed. The connection is represented by 2 channels - one for each direction. I think you might be encountering a deadlock because the producer on one end is not also reading the incoming - so either restructure, or use 2 more threads for the producers. > On Dec 6, 2019, at 10:38 PM, Egon Kocjan <ekoc...@gmail.com> wrote: > > Agreed, I see goroutines in general as a big win. But what I intend to talk > about in the presentation: > - we have two unidirectional flows of data resembling something like a TCP > socket, easy to do with two goroutines with a for loop > - let's add caching, so some requests do not go to the server > - it would be tempting to just combine two goroutines into one and handle > caching in a single loop without using locks (I see developers avoid atomics > and locks if they don't have a lot of previous experience with traditional MT > primitives) > - this is surprisingly difficult to do properly with Go channels, see my > attempts: https://github.com/egonk/chandemo/blob/master/2_3.go > <https://github.com/egonk/chandemo/blob/master/2_3.go> and > https://github.com/egonk/chandemo/blob/master/2_4.go > <https://github.com/egonk/chandemo/blob/master/2_3.go> > - it is easy to do in actor systems, just move the code for both actors into > a single actor! > > The lesson here is that select is not a nice and safe compose statement even > if it appears so at the first glance, do not be afraid to use locks. > > Of course, if somebody comes up with a better implementation than 2_3.go and > 2_4.go, I would be very happy to include it in the talk. > > On Saturday, December 7, 2019 at 4:17:04 AM UTC+1, robert engels wrote: > To clarify, with Go’s very lightweight threads it is “doing the multiplexing > for you” - often only a single CPU is consumed if the producer and consumer > work cannot be parallelized, otherwise you get this concurrency “for free”. > > You are trying to manually perform the multiplexing - you need async > structures to do this well - Go doesn’t really support async by design - and > it’s a much simpler programming model as a result. > >> On Dec 6, 2019, at 12:02 PM, Robert Engels <ren...@ix.netcom.com <>> wrote: >> >> A channel is much closer to a pipe. There are producers and consumers and >> these are typically different threads of execution unless you have an event >> based (async) system - that is not Go. >> >>> On Dec 6, 2019, at 9:30 AM, Egon Kocjan <eko...@gmail.com <>> wrote: >>> >>> >>> There are goroutines in the examples of course, just a single goroutine per >>> bidi channel seems hard. By contrast, I've worked with actor systems before >>> and they are perfectly fine with a single fiber. >>> >>> On Friday, December 6, 2019 at 3:38:20 PM UTC+1, Robert Engels wrote: >>> Channels are designed to be used with multiple go routines - if you’re not >>> you are doing something wrong. >>> >>>> On Dec 6, 2019, at 8:32 AM, Egon Kocjan <eko...@gmail.com <>> wrote: >>>> >>>> >>>> Hello >>>> >>>> I'm preparing a short talk about Go channels and select. More >>>> specifically, I want to show what not to do. I chose a bidirectional >>>> communication channel implementation, because it seems to be a common base >>>> for a lot of problems but hard to implement correctly without using any >>>> extra goroutines. All the code is here: https://github.com/egonk/chandemo >>>> <https://github.com/egonk/chandemo> >>>> >>>> 1_1.go: easy with en extra goroutine (takes 1.2s for million ints) >>>> 2_1.go: nice but completely wrong >>>> 2_2.go: better but still deadlocks >>>> 2_3.go: correct but ugly and slow (takes more than 2s for million ints) >>>> 2_4.go: correct and a bit faster but still ugly (1.8s for million ints) >>>> >>>> So my question: is there a better way of doing it with just nested for and >>>> select and no goroutines? Basically, what would 2_5.go look like? >>>> >>>> Thank you >>>> Egon >>>> >>>> -- >>>> You received this message because you are subscribed to the Google Groups >>>> "golang-nuts" group. >>>> To unsubscribe from this group and stop receiving emails from it, send an >>>> email to golan...@googlegroups.com <>. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/golang-nuts/82830a5d-2bd8-4324-890e-9ae7f5f0fbaf%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/golang-nuts/82830a5d-2bd8-4324-890e-9ae7f5f0fbaf%40googlegroups.com?utm_medium=email&utm_source=footer>. >>> >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "golang-nuts" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to golan...@googlegroups.com <>. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/golang-nuts/bdc57eb0-b26f-4364-87fb-241b0807e8ae%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/golang-nuts/bdc57eb0-b26f-4364-87fb-241b0807e8ae%40googlegroups.com?utm_medium=email&utm_source=footer>. > > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com > <mailto:golang-nuts+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/75d69b4e-4fb7-4f62-8011-f21e2a4c294a%40googlegroups.com > > <https://groups.google.com/d/msgid/golang-nuts/75d69b4e-4fb7-4f62-8011-f21e2a4c294a%40googlegroups.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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