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Re: Lightwight socket IO wrapper

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On Mon, Sep 21, 2015 at 2:39 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
> Chris Angelico <rosuav@gmail.com>:
>
>> On Mon, Sep 21, 2015 at 11:55 AM, Cameron Simpson <cs@zip.com.au> wrote:
>>> Another nice thing about TCP is that wil a little effort you get to
>>> pack multiple data packets (or partial data packets) into a network
>>> packet, etc.
>>
>> Emphatically - a little effort sometimes, and other times no effort at
>> all! If you write a packet of data, then write another one, and
>> another, and another, and another, without waiting for responses,
>> Nagling should combine them automatically. And even if they're not
>> deliberately queued by Nagle's Algorithm, packets can get combined for
>> other reasons. So, yeah! Definitely can help a lot with packet counts
>> on small writes.
>
> Unfortunately, Nagle and delayed ACK, which are both defaults, don't go
> well together (you get nasty 200-millisecond hickups).

Only in the write-write-read scenario. If you write-read-write-read,
or if your reads don't depend on your writes, then Nagle + delayed ACK
works just fine. But if you write a bunch of stuff, then block waiting
for the other end to respond, and then write multiple times, and wait
for a response, _then_ the pair work badly together, yes.

> As for the topic, TCP doesn't need wrappers to abstract away the
> difficult bits. That's a superficially good idea that leads to trouble.

Depends what you're doing - if you're working with a higher level
protocol like HTTP, then abstracting away the difficult bits of TCP is
part of abstracting away the difficult bits of HTTP, and something
like 'requests' is superb. But if you're inventing your own protocol,
directly on top of a BSD socket, then I would agree - just call socket
functions directly. Otherwise you risk nasty surprises when your
file-like object has ridiculous performance problems.

ChrisA

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Thread

Re: Lightwight socket IO wrapper Chris Angelico <rosuav@gmail.com> - 2015-09-21 12:40 +1000
  Re: Lightwight socket IO wrapper Marko Rauhamaa <marko@pacujo.net> - 2015-09-21 07:39 +0300
    Re: Lightwight socket IO wrapper Chris Angelico <rosuav@gmail.com> - 2015-09-21 14:48 +1000
      Re: Lightwight socket IO wrapper Marko Rauhamaa <marko@pacujo.net> - 2015-09-21 09:56 +0300
    Re: Lightwight socket IO wrapper Michael Ströder <michael@stroeder.com> - 2015-09-21 09:02 +0200
      Re: Lightwight socket IO wrapper Marko Rauhamaa <marko@pacujo.net> - 2015-09-21 10:57 +0300
        Re: Lightwight socket IO wrapper Michael Ströder <michael@stroeder.com> - 2015-09-21 10:29 +0200
          Re: Lightwight socket IO wrapper Marko Rauhamaa <marko@pacujo.net> - 2015-09-21 11:47 +0300
            Re: Lightwight socket IO wrapper MRAB <python@mrabarnett.plus.com> - 2015-09-21 13:26 +0100

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