Performance issues when upgrading from ruby ​​1.9.3 to 2.2.2

Question

When upgrading from ruby-1.9.3-p545 to ruby-2.2.2, we experienced a 50% decrease in performance in our application. I have done quite a bit of reading on this subject, and I suspect that this may be the result of changing the way the ruby ​​does garbage collection.

The misconception is that there were no noticeable changes in our server performance. We did not see a surge in memory usage. If garbage collection slows down performance, will we see a surge in memory usage? Is this a sign that performance issues are occurring elsewhere? Is it possible that gems do not play well together?

Answer 1

It seems that the reason for the performance drop is related to garbage collection. We were able to significantly improve performance by installingRUBY_GC_MALLOC_LIMIT=90000000

As a resource, we used the following: https://meta.discourse.org/t/tuning-ruby-and-rails-for-discourse/4126