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disconnect from connection pool before forking still relevant? #1001

jjb opened this Issue Jun 16, 2016 · 3 comments


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jjb commented Jun 16, 2016

I found this buried in the readme:

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

I've never seen this recommendation mentioned in any discussions elsewhere, and the configuration is not included in puma's own heroku plugin

Is the recommendation still relevant? If so, should it go into the heroku plugin? (I can do a PR)


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evanphx commented Jun 20, 2016

@jjb It can't hurt to go into the official heroku plugin. @schneems thoughts?


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schneems commented Jun 20, 2016

Interesting. I guess disconnecting before forking has the same effect as manually connecting after the fork. I prefer that method otherwise if there's a weird race condition where you've done a query in a separate thread or something you might accidentally create another connection maybe?

I don't see adding it as a bad thing, however I also don't entirely think it's necessary. The establish_connection should fix any connection pool problems.

Actually, re-read that comment and I think we should be doing it. It's about connection leaks. Right now you might be left with X connections to the database open that you'll never use for each dyno. Not a big deal for a few dynos but if you've got a lot of them connections in PG aren't free. We should probably add it. Can you send a patch to put it in the plugin @jjb ?


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jjb commented Jun 20, 2016


@jjb jjb closed this Jun 21, 2016

christiannelson added a commit to carbonfive/raygun-rails that referenced this issue Sep 20, 2016

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