Mysql::Error: Lost connection to MySQL server during query

[maxig]

Hi.
Parallel.map(orders, :in_processes => 6) do |order|
ActiveRecord::Base.establish_connection
# some huge calculation
end

And i get this error:
Mysql::Error: Lost connection to MySQL server during query

or this one:
Mysql::Error: MySQL server has gone away

What i did wrong?

[grosser]

Nothing, AR + forking = fooo, if you find a reliable method let me know... (maybe rescue reconnect..., I don't know...)

[wilsonmichael]

What has worked for me is calling ActiveRecord::Base.connection.reconnect! inside the block

Parallel.each( items, in_processes: 4 ) do |item|
  # Reconnect to the database in the new process ( or thread )
  ActiveRecord::Base.connection.reconnect!
  # do stuff ...
end

[grosser]

did this work too ? (would lower the amount of reconnects)

  @reconnected ||= User.connection.reconnect! || true