Leaking is the wrong word. A leak implies that the memory was retained, RAM usage will go up forever and the process will eventually crash as a result. This is

Leaking is the wrong word. A leak implies that the memory was retained, RAM usage will go up forever and the process will eventually crash as a result. This is memory that sidekiq needs to do it's job, allocating strings, hashes, arrays etc. that will all be cleaned up eventually. Larger, more complex objects take up more memory. I.e. strings take up less memory than a hash. What he has done is eliminate the need to allocate so many large objects. This means less GC is needed, and overall performance is increased. See http://www.schneems.com/2015/05/11/how-ruby-uses-memory.html http://www.schneems.com/2015/05/11/how-ruby-uses-memory.html for more info.