Baseline puma worker/thread config

Because we expect fewer I/O waits than Rails apps that connect to the
database over the network, let's start with a baseline config of 1
worker per CPU, 1 thread per worker and tune it from there.

https://edgeguides.rubyonrails.org/tuning_performance_for_deployment.html#puma

config/puma.rb

@@ -1,16 +1,3 @@
-# Puma starts a configurable number of processes (workers) and each process
-# serves each request in a thread from an internal thread pool.
-#
-# You can control the number of workers using ENV["WEB_CONCURRENCY"]. You
-# should only set this value when you want to run 2 or more workers. The
-# default is already 1.
-#
-# Any libraries that use a connection pool or another resource pool should
-# be configured to provide at least as many connections as the number of
-# threads. This includes Active Record's `pool` parameter in `database.yml`.
-threads_count = ENV.fetch("RAILS_MAX_THREADS", 5)
-threads threads_count, threads_count
-
 # Specifies the `port` that Puma will listen on to receive requests; default is 3000.
 port ENV.fetch("PORT", 3000)
 
@@ -29,3 +16,11 @@ control_uri = Rails.env.local? ? "unix://tmp/pumactl.sock" : "auto"
 activate_control_app control_uri, no_token: true
 plugin :yabeda
 plugin :yabeda_prometheus
+
+# Because we expect fewer I/O waits than Rails apps that connect to the
+# database over the network, let's start with a baseline config of 1
+# worker per CPU, 1 thread per worker and tune it from there.
+#
+# https://edgeguides.rubyonrails.org/tuning_performance_for_deployment.html#puma
+workers Concurrent.physical_processor_count
+threads 1, 1