[erlang-questions] Reinserting a message into a gen_server's mailbox

Gleb Peregud <>
Thu Jul 29 21:37:56 CEST 2010


On Thu, Jul 29, 2010 at 21:31, Juan Jose Comellas <> wrote:
> I'm aware that I can do a gen_server:reply/2 from any process, but I was
> planning on issuing the gen_server:reply/2 calls from the gen_server process
> because that's where I'll be queueing up the requests.

Do you need this for doing some kind of throttling? Or to make sure
that these requests are processed one by one serially?

> I'm still curious, though, does the format of these internal messages ever
> change? What happens if I use two different Erlang/OTP versions in my nodes?
> Does the newer VM/library still accept the old version of the messages?

gen_* message format is not documented. So there are no guarantees
that they will not change, so you shouldn't rely on them unless you
are ready to take the risk. AFAIR there's a promise that nodes which
major version differ by one will work together in a cluster (e.g. R13
would work with R14).

Best,
Gleb Peregud


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