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From: Sam Saffron <sam.saffron@gmail.com>
Date: Tue, 5 Dec 2017 10:42:36 +1100
Message-ID: <CAAtdryPUp3hSvrCCqOfs9B-DVsXnJdR=eKED8RzX5Duy5YXBCA@mail.gmail.com>
Subject: Auto scaling workers with unicorn
To: unicorn-public <unicorn-public@bogomips.org>
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List-Id: <unicorn-public.bogomips.org>

I would like to amend Discourse so we "automatically" absorb certain
traffic spikes. As it stands we can only configure unicorn with
num_workers and use TTIN and TTOUT to tune the number on the fly.

I was wondering if you would be open to patching unicorn to allow it
to perform auto-tuning based on raindrops info.

How it could work

1. configure unicorn with min_workers, max_workers, wince_delay, scale_up_delay

2. If queued requests is over 0 for N samples over scale_up_delay, add
a worker up until max_workers

3. If queued requests is 0 for N samples over wince_delay scale down
until you reach min workers

Having this system in place can heavily optimize memory in large
deployments and simplifies provisioning logic quite a lot.

Wondering what you think about this and if you think unicorn should
provide this option?