Updated puma config based on number of cpus

config/puma.rb

@@ -1,34 +1,46 @@
 # frozen_string_literal: true
 
+# Get CPU allocation for container
+def get_container_cpus
+  quota = File.read('/sys/fs/cgroup/cpu/cpu.cfs_quota_us').to_i
+  period = File.read('/sys/fs/cgroup/cpu/cpu.cfs_period_us').to_i
+  (quota.to_f / period).ceil
+rescue
+  # Fallback if files can't be read
+  ENV.fetch("WEB_CONCURRENCY") { 3 }.to_i
+end
+
+# Get the actual CPU allocation
+cpu_allocation = get_container_cpus
+
 # Puma can serve each request in a thread from an internal thread pool.
 #
 # The `threads` method setting takes two numbers: a minimum and maximum. Any libraries that use
 # thread pools should be configured to match the maximum value specified for Puma. Default is set to
 # 5 threads for minimum and maximum; this matches the default thread size of Active Record.
 #
-# ETModel is not thread-safe due to `Current` and similar classes.
+# ETModel is not thread-safe, due to the 'Current' class (and potentially others), so we use 1 thread per worker.
 threads 1, 1
 
+# Use actual container CPU allocation instead of host CPU count
+workers cpu_allocation
+
+# Preload the app before forking to save memory via Copy-On-Write
+preload_app!
+
 # Specifies the `port` that Puma will listen on to receive requests; default is 3000.
-port ENV.fetch('PORT', 3000)
+port        ENV.fetch('PORT')    { 3001 }
 
 # Specifies the `environment` that Puma will run in.
-environment ENV.fetch('RAILS_ENV', 'development')
+environment ENV.fetch('RAILS_ENV'){ 'development' }
 
 # Specifies the `pidfile` that Puma will use.
-pidfile ENV.fetch('PIDFILE', 'tmp/pids/server.pid')
+pidfile ENV.fetch('PIDFILE') { 'tmp/pids/server.pid' }
 
-# Specifies the number of `workers` to boot in clustered mode.
-#
-# Workers are forked web server processes. If using threads and workers together the concurrency of
-# the application would be max `threads` * `workers`. Workers do not work on JRuby or Windows (both
-# of which do not support processes).
-workers ENV.fetch('WEB_CONCURRENCY', 0)
-
-# Use the `preload_app!` method when specifying a `workers` number. This directive tells Puma to
-# first boot the application and load code before forking the application. This takes advantage of
-# Copy On Write process behavior so workers use less memory.
-preload_app!
+# Re-establish connections in each worker
+on_worker_boot do
+  ActiveRecord::Base.establish_connection if defined?(ActiveRecord)
+end
 
 # Allow puma to be restarted by `rails restart` command.
 plugin :tmp_restart