This looks like a bug in the docs; the intention is that datagram protocols
also support flow control. Where does it say so in the docs? Is it the PEP
or the CPython Doc tree?

On Sat, Feb 22, 2014 at 5:12 PM, Christopher Probst <> wrote:

> Hi,
> after looking into the implementation I saw that, for instance,
> _SelectorDatagramTransport calls _maybe_pause_protocol and it's
> counterpart, but the doc says that only Protocol and SubprocessProtocol has
> flow-control support and DatagramProtocol does not.
> I know that udp flow-control is not the same as tcp flow-control, but I'm
> concerned about filling up the internal buffer when writing a lot of
> datagrams. If this is not supported, I would argue that the udp support
> is pretty much broken for data intense application because how would the
> writer know when the internal buffer (and/or kernel level buffer) are full ?
> So, is the doc just not up-to-date or is it an implementation detail of
> tulip ?
> And other question that came up: Are there any plans for coroutine methods
> for udp (like StreamWriter/Reader for TCP) ?
> Also, are there any "dirty" corners somebody heavily working with udp have
> to know ? I'm implementing reliable udp and I would like to use the
> coroutine style instead of callbacks.
> Regards,
> Chris

--Guido van Rossum (

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