Object Allocations on the Web

How many objects does a Rails request allocate? Here are Twitter’s numbers:

  • API: 22,700 objects per request
  • Website: 67,500 objects per request
  • Daemons: 27,900 objects per action

I want them to be lower. Overall, we burn 20% of our front-end CPU on garbage collection, which seems high. Each process handles ~29,000 requests before getting killed by the memory limit, and the GC is triggered about every 30 requests.

This is a pretty damn sad state of affairs with respect to Rails when you consider how highly-tuned Twitter must be at this stage of the game.