Hi,
sorry but as Ryan Tran said, this calculation is not correct regarding to Odoo V14-15.

1.)
With an 8 Core CPU you can theoretically use max. 17 worker (if you have enough memory installed). But you need also CPU power for other processes like OS and Postgres. And by the way the parameter "max_cron_threads" is using/starting 2 worker processes, too. You can see this in the Odoo log after the odoo service starts. So you can add in the "workers" parameter only 15 from your theoretical max. available 17 workers (or less - depends on the max. available memory and installed programs). I'm not sure but I believe that the longpolling process needs also 1 worker (Odoo Documentation: "In multiprocessing, a dedicated LiveChat worker is automatically started and listening on the longpolling port but the client will not connect to it.").

2.)
The values 640MB and 768MB for the memory limits are default values from Odoo V10 and not state of the art in the year 2021. The default values from Odoo V14-15 are 2048 MB and 2560 MB per Worker.

3.)
According to the Odoo documentation are the memory limit values specified per worker and are no total values as you have added. An better formula will be -> Available Memory for Odoo = (Max. Memory in byte - needed Memory for OS and other Apps like Postgres) / max. workers

Original text from the Odoo V15 manual (odoo-bin --help):
--limit-memory-soft=LIMIT_MEMORY_SOFT
Maximum allowed virtual memory per worker (in bytes), when reached the worker be reset after the current request (default 2048MiB).

--limit-memory-hard=LIMIT_MEMORY_HARD
Maximum allowed virtual memory per worker (in bytes), when reached, any memory allocation will fail (default 2560MiB).

4.)
In your calculation is specified round about 13,7 GB RAM per worker for the hard memory limit. You configured 19 workes, so you need theoretically 260 GB Memory when all workers produce an heavy load. But with this settings already if 1-2 workers produce an high load you will receive an out of momory error in your operation system and your linux will freeze (e.g. when a user create an pdf report with 200-500 pages).

Hi Nicky,

Is the calculation of memory indeed per worker or is it as per documentation of Odoo itself, per server:

https://www.odoo.com/documentation/16.0/administration/install/deploy.html#id5

Configuration sample
Server with 4 CPU, 8 Thread

60 concurrent users

60 users / 6 = 10 <- theoretical number of worker needed

(4 * 2) + 1 = 9 <- theoretical maximal number of worker

We’ll use 8 workers + 1 for cron. We’ll also use a monitoring system to measure cpu load, and check if it’s between 7 and 7.5 .

RAM = 9 * ((0.8*150) + (0.2*1024)) ~= 3Go RAM for Odoo

in /etc/odoo.conf:

[options]
limit_memory_hard = 1677721600
limit_memory_soft = 629145600
limit_request = 8192
limit_time_cpu = 600
limit_time_real = 1200
max_cron_threads = 1
workers = 8

After digging into this some more it looks like Nicky's explanation is correct. The source code for the file config.py (line 325 and on) confirms that settings like limit_memory_hard are PER worker.

https://github.com/odoo/odoo/blob/fa58938b3e2477f0db22cc31d4f5e6b5024f478b/odoo/tools/config.py

Further, it seems that the calculations given assume that Odoo is the only service running on the system. This may or may not be the case of course and in that case, available resources should be reduced accordingly.

the calculation is correct.