Mostly Sidekiq. Even with virtually unlimited resources sidekiq gave me a lot of headaches. Funny enough I believe I finally figured it out, after years! It wa

Mostly Sidekiq. Even with virtually unlimited resources sidekiq gave me a lot of headaches. Funny enough I believe I finally figured it out, after years! It was hanging on mail notification jobs because the MTA wasn't properly setup. Once the MTA was fixed sidekiq was working better and I was also receiving mail notifications. Even so, syncing with AD I get internal names like shortname@addomain.local and most users don't update their profile. Thankfully the MTA just queues them and discards them without blocking sidekiq. I've worked a lot with async jobs in Python using both RMQ and rq, I don't see why sidekiq should be such an issue. I've never had issues like that myself in my own projects. Also felt that it was hard to manage compared to my own experiences with job management in Python. Adding to the frustration was having to understand a (to me) foreign language like Ruby. Something I never wanted to learn and avoided successfully. I ended up having to write a little bit of code that could kill sidekiq jobs because I couldn't figure out how to do it through any interface provided by Gitlab.