Rails 7: How to handle database transactions in a multi-threaded job while avoiding deadlocks?
Hey everyone, I'm running into an issue that's driving me crazy... I've tried everything I can think of but I'm following best practices but I've searched everywhere and can't find a clear answer... I'm working with deadlocks when trying to run a background job that updates multiple records in a Rails 7 application using Active Job with Sidekiq. My job processes data in a multi-threaded manner, and it sometimes leads to the following behavior: ``` ActiveRecord::Deadlocked ``` I've tried wrapping my ActiveRecord calls within a `transaction` block, but it doesn't seem to resolve the scenario. Here’s a simplified version of my code: ```ruby class MyJob < ApplicationJob queue_as :default def perform(record_ids) ActiveRecord::Base.transaction do record_ids.each do |id| record = MyModel.lock.find(id) # Some complex business logic that might call update on the record record.update!(status: 'processed') end end end end ``` The `lock` method is supposed to prevent other transactions from modifying the records while I’m processing them, but it appears that concurrent jobs are still causing deadlocks. I've also ensured that my database (PostgreSQL 14) has adequate settings for handling isolated transactions. I’ve looked into using a retry mechanism for the job, but that feels like more of a workaround than a solution. Is there a better way to manage these transactions or to refactor the code to avoid deadlocks altogether? Any insights or best practices would be greatly appreciated! For context: I'm using Ruby on Debian. Thanks, I really appreciate it! Hoping someone can shed some light on this. I'm on CentOS using the latest version of Ruby. Thanks, I really appreciate it!