On Fri, Aug 29, 2014 at 10:10 AM, Carl Inglis <[email protected]> wrote:
> I suspect you're looking for something like this:
> http://www.perlmonks.org/?node_id=66135
>
> In fact, it's specifically mentioned in the Perl Cookbook:
> http://docstore.mik.ua/orelly/perl/cookbook/ch07_15.htm
The comments on the first URL is worrying, but I don't believe that it
would solve my issue. Lets take the following out of RFC4664 as an
example. This is an actual example of a communication stream between
a client and the perl server, the socket is already established, and
communication is flowing between the two parties. [C] indicates what
the client is sending to the server, and [S] indicates the responses
the server sends to the client. My comments added with # and thus
does not form part of the communication stream.
[C] TAKETHIS <[email protected]>
[C] Path: pathost!demo!somewhere!not-for-mail
[C] From: "Demo User" <[email protected]>
[C] Newsgroups: misc.test
[C] Subject: I am just a test article
[C] Date: 6 Oct 1998 04:38:40 -0500
[C] Organization: An Example Com, San Jose, CA
[C] Message-ID: <[email protected]>
[C]
[C] This is just a test article.
[C] .
# . indicates the end of the article. Perl now starts to do work,
processing the article it received. As this process takes time, the
main while (1) { loop reading from the socket is now blocked, causing
the server not to read any more from the socket until after the
article has been dealt with.
[C] TAKETHIS <[email protected]>
[C] Path: pathost!demo!somewhere!not-for-mail
[C] From: "Demo User" <[email protected]>
[C] Newsgroups: misc.test
[C] Subject: I am just a test article
[C] Date: 6 Oct 1998 04:38:40 -0500
[C] Organization: An Example Com, San Jose, CA
[C] Message-ID: <[email protected]>
[C]
[C] This is just a test article.
[C] .
# Perl server only NOW responds with an acceptance code for the first article.
[S] 239 <[email protected]>
We have effectively now COMPLETELY missed the second article in our
while (1) loop, as perl did not read from the socket WHILST processing
the article.
When you multiply the above example and think that you can effectively
be receiving up to 100 (if not more) TAKETHIS commands per second, and
that it takes (on average) say 100ms to "deal" with an article
received... I'm sure you can understand the economics at scale here as
to why this is important, and what I mean by non blocking...
The whole while (1) { read from socket; do work; respond; }; isn't
going to work. The moment you "do work", you block reading from the
socket until such time that the work has been completed. I don't
know how to be clearer about this.
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