Database connection pooling configuration

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                  production:
  adapter: postgresql
  encoding: unicode
  pool: <%= ENV.fetch("RAILS_MAX_THREADS", 5) %>
  timeout: 5000
  checkout_timeout: 5
  reaping_frequency: 10
  url: <%= ENV['DATABASE_URL'] %>

                  max_threads_count = ENV.fetch("RAILS_MAX_THREADS", 5)
min_threads_count = ENV.fetch("RAILS_MIN_THREADS") { max_threads_count }
threads min_threads_count, max_threads_count

worker_timeout 3600 if ENV.fetch("RAILS_ENV", "development") == "development"

port ENV.fetch("PORT", 3000)
environment ENV.fetch("RAILS_ENV", "development")

# Preload app for better memory efficiency with workers
preload_app!

on_worker_boot do
  ActiveRecord::Base.establish_connection
end

Properly configured connection pools prevent ActiveRecord::ConnectionTimeoutError during traffic spikes while avoiding resource waste. The pool size should match your application's concurrency needs—for Puma with 5 threads per worker, I set pool: 5 in database.yml. I also configure checkout_timeout to fail fast when the pool is exhausted rather than blocking indefinitely. In containerized environments, I calculate the total pool size across all instances to stay under the database's connection limit. The reaping_frequency setting helps recover leaked connections that weren't properly released. Monitoring active connections and pool saturation reveals whether I need to scale horizontally or tune query performance.

Alex Kumar

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Database connection pooling configuration

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