Simplify autotune.php WEB_CONCURRENCY output a bit more

[dzuelke]

For consistency with previous versions of the buildpack, and to reduce potential for confusion (think e.g. number of cores on shared dynos), the CPU core count is now only printed in verbose mode or when there is no ${DYNO} env var.

However, should the log_2 CPU core count based WEB_CONCURRENCY limit kick in, a notice is now always printed.

Also adds -h/--help switches, and different verbosity levels.

Related to #685 and #684.

Fixes #689.

GUS-W-14634717

[dzuelke]

Output examples (all with memory_limit = 128M).

1X dyno:

Available RAM is 512M Bytes
PHP memory_limit is 128M Bytes

Container with 512M Bytes RAM and 8 CPU cores:

Available RAM is 512M Bytes
Number of CPU cores is 8
PHP memory_limit is 128M Bytes
Calculated number of workers based on RAM and CPU cores is 32
Maximum number of workers that fit available RAM at memory_limit is 4
Limiting number of workers to 4

Performance-M dyno with --verbose option:

Available RAM is 2560M Bytes
Number of CPU cores is 2
Determining scaling factor based on a memory_limit of 128M
Scaling factor is 5
PHP memory_limit is 128M Bytes
Calculated number of workers based on RAM and CPU cores is 20

Container with 4G Bytes RAM and 2 CPU cores:

Available RAM is 4G Bytes
Number of CPU cores is 2
PHP memory_limit is 128M Bytes
Calculated number of workers based on RAM and CPU cores is 20
Maximum number of workers that fit available RAM at memory_limit is 32
Limiting number of workers to 20

[edmorley]

CI is failing

[jwage]

Suddenly I am getting this:

2024-02-10T02:08:34.086250+00:00 app[web.2]: DOCUMENT_ROOT changed to 'public/'
2024-02-10T02:08:34.144353+00:00 app[web.2]: Using Nginx server-level configuration include 'nginx.conf'
2024-02-10T02:08:34.239393+00:00 app[web.2]: $WEB_CONCURRENCY env var is set, skipping automatic calculation
2024-02-10T02:08:34.254244+00:00 app[web.2]: Starting php-fpm with 4 workers...
2024-02-10T02:08:34.367235+00:00 app[web.2]: Starting nginx...

It is on a private-s dyno type with 1024MB of memory.

My public/.user.ini looks like this:

memory_limit = 32M
max_execution_time = 20

I used to get 32 workers.

I don't have a $WEB_CONCURRENCY environment variable set anywhere in my settings or application.

[edmorley]

@jwage Hi! Trying a new app now (which doesn't have WEB_CONCURRENCY set), I don't get that output, but instead:

2024-02-10T10:14:36.346843+00:00 app[web.1]: DOCUMENT_ROOT changed to 'web/'
2024-02-10T10:14:36.521889+00:00 app[web.1]: Available RAM is 512M Bytes
2024-02-10T10:14:36.521911+00:00 app[web.1]: PHP memory_limit is 128M Bytes
2024-02-10T10:14:36.545437+00:00 app[web.1]: Starting php-fpm with 4 workers...

Is it possible you are using another buildpack alongside the PHP buildpack, which is running after the PHP buildpack, and so setting it's own WEB_CONCURRENCY value?

If so, then you need to make sure the PHP buildpack runs as the last buildpack (presuming it's the primary language for your app), as mentioned on:
https://devcenter.heroku.com/articles/using-multiple-buildpacks-for-an-app#adding-a-buildpack

The buildpack for the primary language of your app should always be the last buildpack in the list. This ensures that defaults for that primary language are applied instead of those for another language, and allows Heroku to correctly detect the primary language of your app.

[jwage]

That is it. I need the PHP buildpack to be first for another reason. I suppose I will set the env variable manually to work around this.

I reordered node to be after PHP because the composer install for PHP makes something available that is necessary for the node build to succeed.