Welcome to Puma 7: Romantic Warrior.

Puma 7 brings better tail latency for keepalive-heavy traffic, support for fiber-per-request runtimes, and a handful of cleanup and compatibility changes across the server.

Here's what you should do:

1. Review the Upgrade section below to look for breaking changes that could affect you.
2. Upgrade to version 7.0 in your Gemfile and deploy.
3. Open up a new bug issue if you find any problems.
4. Join us in building Puma! We welcome first-timers. See CONTRIBUTING.md.

For a complete list of changes, see History.md.

What's New

Puma 7 is focused on request lifecycle improvements and long-request correctness.

1. Better tail behavior for keepalive connections. Puma 7 includes a high-effort fix for long tail response behavior with keepalive clients.
2. Fiber-per-request support. Puma now supports fiber-per-request execution.
3. rack.response_finished support. Puma now supports the Rack hook for response completion.
4. Custom request logging support. You can plug in a custom logger for request logs.

Upgrade

Check the following list to see if you're depending on any of these behaviors:

1. The default max_keep_alive is now 999.
2. The default persistent_timeout is now 65 seconds.
3. Hook methods now raise ArgumentError if called without a block.
4. For Rack > 3.1, Puma no longer sets env['HTTP_VERSION'].
5. Puma::Runner#ruby_engine has been removed.
6. preload_app! is now the default in cluster mode. If you need the old behavior, set preload_app! false explicitly.
7. Puma::Configuration must be clamp-ed before reading values.
8. Response headers are now normalized to lowercase.
9. The minimum supported Ruby version is now 3.0.
10. Callback hook names have been renamed:

Old hook name	New hook name
on_worker_boot	before_worker_boot
on_worker_shutdown	before_worker_shutdown
on_restart	before_restart
on_booted	after_booted
on_stopped	after_stopped
on_refork	before_refork
on_thread_start	before_thread_start
on_thread_exit	before_thread_exit
on_worker_fork	before_worker_fork

Then, update your Gemfile:

gem 'puma', '< 8'