Do threads in rails automatically open database connections?

Question

I have a rails app running on Heroku that makes use of threads, and it occasionally runs into database connection errors. Is this just because I am accessing the database within the threads or does each thread automatically open a database connection? I would like to learn more about threading in rails, and any resources are appreciated.

Answer 1

This question varies largely depending on how many instances you have running, how many requests your receiving, and more importantly your database. Databases can and will have a maximum number of concurrent connections. You can read more about Heroku/concurrent connections here in the Heroku official documentary , it's probably more informative than what I can tell you in a single comment.

That being said, your question was a little vague and it's hard to figure out what's going on. Can you tell us a little more about what error you're getting (like the specific error) and maybe a small backtrace? Are you getting these errors on the same pages or different pages? Would you say your site is particularly high traffic?