I know that Discourse setup provides sane defaults for most occasions nowadays, but I still want to ask some guidance on optimal settings. It seems that we will get a hosting partner that provides us with the server and what is on the table is this VPS: 6x vCore CPUs (Xeons @ 2.40GHz, I beleive) 8…

The usual, which is DB gets 1/4 of memory Up to two unicorns per “real” CPU core (I’d limit to 8 for now though)

Found the limits of our setup yesterday, with about 400+ concurrent sessions and many of them being logged in, actively polling and chatting. The day before we delivered 138k page views without a hitch. The bottleneck was the number of unicorns (8). We only reached about 35% CPU loads and there wer…

With these changes the amount of free memory has reduced from 2GB to 1GB, so roughly -0.5 gigs per unicorn added. Is there a recommendation for the amount of RAM to keep free, thus available for Linux to use as disk cache? I have 1/4 of the RAM (=2GB) allocated to the database buffer.

Increasing the number of unicorn workers to suit your CPU and RAM capacity is perfectly reasonable. The “two unicorns per core” guideline is a starting figure. CPUs differ (wildly) in their performance, and VPSes make that even more complicated (because you can never tell who else is on the box an…

Thanks Matt. Crystal clear and informative, as usual. Here is a some more nerd porn. Our API requests for this year. This is what it looks like when there is a hockey league transfer deadline on the 15th of Feb at 23:59 local time. [imagen]

What tools are you using for monitoring the api requests, which is shown from your image?

If I’m not mistaken, that’s Discourse’s built in report visualizer. Go to yoursite.com/admin, then click any of the statistic titles.

[imagen] codinghorror: The usual, which is DB gets 1/4 of memory Up to two unicorns per “real” CPU core (I’d limit to 8 for now though) Bump. So are you saying 8 Unicorns is the upper limit on any server? I have a server with 8x CPU and was thinking changing the config to use 16?

Maybe, it depends how much traffic you have. 16 unicorns sitting around doing nothing and waiting for incoming requests would not get you much.

800k-1.2m pageviews/month. Discourse runs buttery smooth most of the time but then if we ever get 300 concurrent users it grinds to a halt. Already have db_shared_buffers configured to 25% of the host’s 32gb RAM, looking for more possible fixes.

Optimizing the number of Unicorns and buffer size

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codinghorror (Jeff Atwood) 13 Octubre, 2016 22:11 2

The usual, which is

DB gets 1/4 of memory
Up to two unicorns per “real” CPU core (I’d limit to 8 for now though)

Tema		Respuestas	Vistas
High CPU usage (Ruby) Support server-resources	20	1053	3 Febrero 2025
Recommendation for number of workers: cores × 2? Self-hosting	16	701	29 Abril 2025
Limiting the number of unicorns, memory usage and swapping Self-hosting server-resources	4	1021	11 Noviembre 2023
Digital Ocean Droplet Size Self-hosting	6	1304	19 Agosto 2019
Tuning a Discourse server for performance Self-hosting hosting	11	3085	4 Abril 2022

Optimizing the number of Unicorns and buffer size

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