unicorn Ruby/Rack server user+dev discussion/patches/pulls/bugs/help
 help / color / mirror / code / Atom feed
From: Bertrand Paquet <bertrand.paquet@doctolib.com>
To: unicorn-public@bogomips.org
Subject: Traffic priority with Unicorn
Date: Mon, 16 Dec 2019 23:34:35 +0100	[thread overview]
Message-ID: <CANCGK7nU=AuO--z-Q9YLSiHttZSCJTJAW4XeNyOByXivfGmihg@mail.gmail.com> (raw)

Hello,

I would like to introduce some traffic priority in Unicorn. The goal
is to keep critical endpoints online even if the application is
slowing down a lot.

The idea is to classify the request at nginx level (by vhost, http
path, header or whatever), and send the queries to two different
unicorn sockets (opened by the same unicorn instance): one for high
priority request, one for low priority request.
I need to do some small modifications [1] in the unicorn worker loop
to process high priority requests first. It seems to work:
- I launch a first apache bench toward the low priority port
- I launch a second apache bench toward the high priority port
- Unicorn handles the queries only for that one, and stop answering to
the low priority traffic

The tradeoff are
- No more "bet"[2] on low priority traffic. This is probably slowing
down a little bit the low  priority traffic.
- This approach is only low / high. Not sure if I can extend it for 3
(or more) level of priority without a non negligible performance
impact (because of the "bet" above).

Do you think this approach is correct?
Do you have any better idea to have some traffic prioritization?
(Another idea is to have dedicated workers for each priority class.
This approach has other downsides, I would like to avoid it).
Is it something we can  introduce in Unicorn (not as default
behaviour, but as a configuration option)?

Thx for any opinion.

Bertrand

[1] https://github.com/bpaquet/unicorn/commit/58d6ba2805d4399f680f97eefff82c407e0ed30f#
[2] https://bogomips.org/unicorn.git/tree/lib/unicorn/http_server.rb#n707

             reply	other threads:[~2019-12-16 22:34 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-16 22:34 Bertrand Paquet [this message]
2019-12-17  5:12 ` Traffic priority with Unicorn Eric Wong
2019-12-18 22:06   ` Bertrand Paquet

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://yhbt.net/unicorn/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CANCGK7nU=AuO--z-Q9YLSiHttZSCJTJAW4XeNyOByXivfGmihg@mail.gmail.com' \
    --to=bertrand.paquet@doctolib.com \
    --cc=unicorn-public@bogomips.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://yhbt.net/unicorn.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).