There are ways to control the framing but in my experience a pseudo multicast scenario is best implemented with a proprietary protocol. You can do this easily on top of other transports Luke grpc/protobufs.
> On Dec 23, 2020, at 5:20 PM, Matthew Zimmerman <mzimmer...@gmail.com> wrote: > > > If you would "reset" each client with a new decoder each time you make a new > encoder, everything should work fine. Just would take some coordination. > >> On Wed, Dec 23, 2020, 6:08 PM Artur Vianna <lordhowen...@gmail.com> wrote: >> I will look into other protocols, although for now the performance is not an >> issue in servers with less than 100 players. >> >> The problem with io.MultiWriter is that a player inside the group may >> disconnect or a new player may come in. This means a new io.MultiWriter must >> be created each time you dispatch, since the group may have changed in the >> meantime. This would also need a new encoder and then the "duplicate type >> received" happens. >> >>> On Wed, 23 Dec 2020, 19:58 'Axel Wagner' via golang-nuts, >>> <golang-nuts@googlegroups.com> wrote: >>> The issue with that approach is that gob keeps state about which >>> type-information it still has to send. So if you encode to, say, a >>> bytes.Buffer, it would encode all type-info on every message sent, which is >>> a significant overhead. >>> TBH, I don't understand why `io.MultiWriter` wouldn't work. It would be >>> helpful to see the code that causes the error message OP is seeing. >>> >>> However, really, gob just doesn't provide a good API for this sorta thing, >>> as mentioned. The format itself is fine, but the stateful connection means >>> that if you don't want to write *exactly* the same data in exactly the same >>> order to all connections (which can perform poorly and lead to operational >>> problems with timeouts and intermittently lost connections and the like), >>> you are going to have a bad time. >>> You honestly would fare better with a full-fledged RPC framework such as >>> gRPC. Or, if you don't want the overhead of its IDL, even json. Because at >>> least the "encode once, send to each client" is trivial to solve with that. >>> >>> But, that's just my 2¢ :) >>> >>>> On Wed, Dec 23, 2020 at 11:43 PM Robert Engels <reng...@ix.netcom.com> >>>> wrote: >>>> Yes, that is why you need to create your own protocol. Use the gob to >>>> encode to a buffer then send the buffer on each of the connections using >>>> your protocol. >>>> >>>>>> On Dec 23, 2020, at 4:19 PM, Matthew Zimmerman <mzimmer...@gmail.com> >>>>>> wrote: >>>>>> >>>>> >>>>> My understanding is that gob streams are unique. >>>>> >>>>> From https://golang.org/pkg/encoding/gob/ >>>>> "A stream of gobs is self-describing. Each data item in the stream is >>>>> preceded by a specification of its type, expressed in terms of a small >>>>> set of predefined types." >>>>> >>>>> In my own rudimentary understanding/terms, it sends the struct definition >>>>> once, then uses shorthand for it afterwards. E.g, how many bytes and >>>>> what order. If you mix and match streams that send definitions in >>>>> different orders, then chaos ensues. >>>>> >>>>> I think this is why people use other encoders in the scenario you're >>>>> taking about. For a one to one stream gob works great, but in this multi >>>>> scenario I don't think it does. >>>>> >>>>> Matt >>>>> >>>>>> On Wed, Dec 23, 2020, 5:07 PM Artur Vianna <lordhowen...@gmail.com> >>>>>> wrote: >>>>>> If i create a bytes.Buffer and a gob.Encoder, each time i write to a >>>>>> group of connections i get "duplicate type received" and if i try and >>>>>> reuse the encoder, i get "corrupted data" and "unknown type". >>>>>> It seems i can't use both net.Conn.Write and gob.Encoder.Encode in the >>>>>> same connection, i will try always encoding to a buffer in both unicast >>>>>> and multicast like you said and report if it works. >>>>>> >>>>>>> On Wed, 23 Dec 2020, 18:49 Robert Engels, <reng...@ix.netcom.com> wrote: >>>>>>> You need to encode once to a byte array then send the byte array on >>>>>>> each connection. >>>>>>> >>>>>>>>> On Dec 23, 2020, at 3:45 PM, meera <lordhowen...@gmail.com> wrote: >>>>>>>>> >>>>>>>> >>>>>>>> I am trying to create a package for game servers using gob. The >>>>>>>> current approach is an application level multicasting over TCP, having >>>>>>>> a gob encoder and decoder for each player connection, and set up a >>>>>>>> goroutine to receive and another to dispatch for each one. The code >>>>>>>> for the dispatcher is here. But summarized, it simply receives data >>>>>>>> from a channel and encodes it. >>>>>>>> >>>>>>>> The problem is that if i want to transmit a single piece of data to >>>>>>>> all players, this piece of data is encoded again and again for each >>>>>>>> connection, doing duplicate work. With less than 100 players this is >>>>>>>> not a problem, but with 300+ my machine is at almost 100% usage and >>>>>>>> the profiler shows that most of it is spent on encoding. Here's the >>>>>>>> issue on github. >>>>>>>> >>>>>>>> I tryied using a io.MultiWriter but gob complains of duplicate type >>>>>>>> received, and if i try to write the raw bytes from the gob.Encoder i >>>>>>>> get corrupted data. An option is using UDP Broadcasting but since gob >>>>>>>> expects a stream, i'm affraid i will run into unexpected behavior when >>>>>>>> packets start to be lost and fragmented. >>>>>>>> >>>>>>>> Does gob expect a single encoder and decoder to own the stream? Not >>>>>>>> allowing two encoders on the server for one decoder on the client? >>>>>>>> -- >>>>>>>> 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. >>>>>>>> To view this discussion on the web visit >>>>>>>> https://groups.google.com/d/msgid/golang-nuts/0562184e-bbcc-44c9-adbf-37e8d5411c7cn%40googlegroups.com. >>>>>> >>>>>> -- >>>>>> 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. >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/d/msgid/golang-nuts/CAE%3DAWBXN46idvqUbCsGs%2BZbZt%2BCj4MowJ4Ozj3_U9_6-68OWDw%40mail.gmail.com. >>>> >>>> -- >>>> 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. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/golang-nuts/214752B6-2666-4892-A9B8-E4BC4127FD42%40ix.netcom.com. >>> >>> -- >>> 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. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/golang-nuts/CAEkBMfGWtULh8Q3Jqu_gq5m5Si4PvJ1oVSZY7DVhu%3D6hGK83bg%40mail.gmail.com. >> >> -- >> 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. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/CAE%3DAWBUsmp2sbiEh%3D3z0cC9EhjLig%2B8exXyA05YngBJ-tsC_uA%40mail.gmail.com. > > -- > 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. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CAD53Lr5yREUMGwgwk%3D5G%2BTDDipRLUKLc1SvPdsWsW_6mjVqvzQ%40mail.gmail.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. 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