Disconnects all connections in the pool before forking.

[frodsan]

Taken from this discussion: puma/puma#1001

If you're preloading your application and using ActiveRecord, it's recommended that you close any connections to the database here to prevent connection leakage:

# config/puma.rb
before_fork do
  ActiveRecord::Base.connection_pool.disconnect!
end

/cc @schneems

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[maclover7]

cc @evanphx

[evanphx]

Seems like good advice. Only matters if initializers make queries.

[pixeltrix]

If we have the before_fork block uncommented then uncommenting the on_worker_boot code becomes redundant doesn't it since Active Record will detect there isn't an active connection and establish one itself. I guess there's a possible scenario where you might want to not preload your app - too much memory mainly 😄

[schneems]

I think this is fine. The issue here isn't that the app won't be able to connect to the database but more that the master server will potentially have open connections that aren't being used. For postgres the number of open connections can be a big problem on larger apps. Explicitly disconnecting before forking would prevent any accidentally opened connections from hanging around longer than is needed.

[kaspth]

r? @pixeltrix @schneems

[fxn]

Please remember "Active Record" has a space. Fixed in 1b6f3a2.