diff --git a/Gemfile.lock b/Gemfile.lock
index aefb50e315a36..a5cf0757f8556 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -89,7 +89,7 @@ PATH
     activesupport (8.0.0.alpha)
       base64
       bigdecimal
-      concurrent-ruby (~> 1.0, >= 1.0.2)
+      concurrent-ruby (~> 1.0, >= 1.3.1)
       connection_pool (>= 2.2.5)
       drb
       i18n (>= 1.6, < 2)
@@ -182,7 +182,7 @@ GEM
     cgi (0.4.1)
     chef-utils (18.3.0)
       concurrent-ruby
-    concurrent-ruby (1.2.2)
+    concurrent-ruby (1.3.1)
     connection_pool (2.4.1)
     crack (0.4.5)
       rexml
diff --git a/activesupport/activesupport.gemspec b/activesupport/activesupport.gemspec
index 17fb20f2a4c3d..4e4f6514925ea 100644
--- a/activesupport/activesupport.gemspec
+++ b/activesupport/activesupport.gemspec
@@ -36,7 +36,7 @@ Gem::Specification.new do |s|
 
   s.add_dependency "i18n",            ">= 1.6", "< 2"
   s.add_dependency "tzinfo",          "~> 2.0", ">= 2.0.5"
-  s.add_dependency "concurrent-ruby", "~> 1.0", ">= 1.0.2"
+  s.add_dependency "concurrent-ruby", "~> 1.0", ">= 1.3.1"
   s.add_dependency "connection_pool", ">= 2.2.5"
   s.add_dependency "minitest",        ">= 5.1"
   s.add_dependency "base64"
diff --git a/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt
index e0364130c2e68..f976b8aa37112 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/puma.rb.tt
@@ -32,10 +32,9 @@ when "production"
   # If you are running more than 1 thread per process, the workers count
   # should be equal to the number of processors (CPU cores) in production.
   #
-  # It defaults to 1 because it's impossible to reliably detect how many
-  # CPU cores are available. Make sure to set the `WEB_CONCURRENCY` environment
-  # variable to match the number of processors.
-  workers_count = Integer(ENV.fetch("WEB_CONCURRENCY", 1))
+  # Automatically detect the number of available processors in production.
+  require "concurrent-ruby"
+  workers_count = Integer(ENV.fetch("WEB_CONCURRENCY") { Concurrent.available_processor_count })
   workers workers_count if workers_count > 1
 
   preload_app!