How to manage opening and closing database connections while working with activerecords and multiple threads

ruby-on-rails multithreading activerecord

To prevent connection leak in multi threads, you have to manage the connection manually. You can try:

Thread.new do  ActiveRecord::Base.connection_pool.with_connection do    # Do whatever  endend

One problem of ActiveRecord::Base.connection_pool.with_connection is that it always prepare a connection even if the code inside does not need it.

We can improve it a little bit by using ActiveRecord::Base.connection_pool.release_connection:

Thread.new do  begin    # Do whatever  ensure    ActiveRecord::Base.connection_pool.release_connection  endend

ruby-on-rails multithreading activerecord

if you want to run in N threads, make sure you have N connections in the pool

#  ActiveRecord::Base.connection_config#  # => {pool: 5, timeout: 5000, database: "db/development.sqlite3", adapter: "sqlite3"}

otherwise you will be able to fetch a connection from the pool.

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