I haven't been able to repro this using the test you attached to issue 153. But I don't have another machine available, I've only tried localhost on OSX (10.9) and from that same box to a local virtual machine running Ubunu. The receiving end just throws away the data -- is that your test setup too? I used "while 1: s.recv(10000); n += 1" in an interactive Python shell.
I do see packet loss (just counting packets received and packets sent) but no exceptions nor does pause_writing() ever get called. From putting some print()s in the code it looks like the sendto() operation always immediately succeeds. The errno has a name: errno.ENOBUFS -- it's 55 on OSX, but 105 on Ubuntu. Perhaps you can elaborate on your test setup? On Sun, Feb 23, 2014 at 11:29 AM, Christopher Probst < foxnet.develo...@googlemail.com> wrote: > Ok, I tried it now with 180 bytes packet and it does not occur, I guess > that my lan connection(gigabit) is too fast that those packets get queued > up. Or OSX decide whether or not to queue those packets based on the size. > But this seems to be heavily os dependent . > > Am Sonntag, 23. Februar 2014 20:12:46 UTC+1 schrieb Guido van Rossum: >> >> Have you tried reducing the write buffer size? >> On Feb 23, 2014 10:41 AM, "Christopher Probst" <foxnet.d...@googlemail. >> com> wrote: >> >>> I saw this in the official 3.4rc1 doc. >>> >>> The doc says, that flow-control callbacks are valid for Protocols and >>> SubprocessProtocols, but DatagramProtocol is not specified. >>> >>> Though I'm happy that Datagram control flow is officially supported I >>> have now an other problem which is directly connected with this issue. >>> Using OSX10.9.1 and python 3.3 sending a lot of udp packets actually >>> does not cause the flow-control to be activated but throws an OSError(55 *No >>> buffer space available)* . >>> >>> After googling around for hours I found out that this is a BSD(probably >>> OS X only) thing. On linux the control-flow works as expected. >>> >>> I listed an issue for this in your tulip repo: >>> Issue 153 <https://code.google.com/p/tulip/issues/detail?id=153> >>> >>> I think that this is really not a python bug, but the way BSD/OSX >>> handles too much udp packets (the socket sdnbuf option is kind of ignored >>> by OSX). I've read that windows actually handles udp overload in a similiar >>> way as BSD does. Though i don't have a windows machine this should probably >>> be tested to confirm or disprove this issue. >>> >>> PS: >>> 18.5.3.2.5. Flow control >>> callbacks<http://docs.python.org/3.4/library/asyncio-protocol.html#flow-control-callbacks> >>> >>> These callbacks may be called on >>> Protocol<http://docs.python.org/3.4/library/asyncio-protocol.html#asyncio.Protocol> >>> and >>> SubprocessProtocol<http://docs.python.org/3.4/library/asyncio-protocol.html#asyncio.SubprocessProtocol> >>> instances: >>> BaseProtocol.pause_writing()<http://docs.python.org/3.4/library/asyncio-protocol.html#asyncio.BaseProtocol.pause_writing> >>> >>> Called when the transport's buffer goes over the high-water mark. >>> BaseProtocol.resume_writing()<http://docs.python.org/3.4/library/asyncio-protocol.html#asyncio.BaseProtocol.resume_writing> >>> >>> Called when the transport's buffer drains below the low-water mark. >>> >>> >>> >>> >>> Am Sonntag, 23. Februar 2014 18:56:42 UTC+1 schrieb Guido van Rossum: >>>> >>>> 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 < >>>> foxnet.d...@googlemail.com> 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 (python.org/~guido) >>>> >>> -- --Guido van Rossum (python.org/~guido)
