[ruby/rack] Set puma workers to 1.25 * nproc (#10442)

WEB_CONCURRENCY=auto sets the number of workers to the number of
processors. Setting it to 1.25 the number of processors seems to
perform better.

Author: p8

frameworks/Ruby/rack/config/puma.rb

@@ -1,4 +1,4 @@
-if ENV.fetch('WEB_CONCURRENCY') == 'auto'
+if ENV.fetch('WEB_CONCURRENCY').to_i > 1
   before_fork do
     Sequel::DATABASES.each(&:disconnect)
   end

frameworks/Ruby/rack/rack.dockerfile

@@ -17,9 +17,9 @@ RUN bundle install --jobs=8
 
 COPY . .
 
-ENV WEB_CONCURRENCY=auto
 ENV MAX_THREADS=5
 
 EXPOSE 8080
 
-CMD bundle exec puma -C config/puma.rb -b tcp://0.0.0.0:8080 -e production
+CMD export WEB_CONCURRENCY=$(($(nproc)*5/4)) && \
+    bundle exec puma -C config/puma.rb -b tcp://0.0.0.0:8080 -e production