Notes from RubyConf 2017 AU talks

Reinvesting in Ruby by Tim Riley

Video

• Rails was defining the Ruby ecosystem, time to explore other alternatives
• Introduces dry-rb gems on a blog post example
• Minimalistic, single-responsibility, composable gems for common tasks
• dry-validation, dry-monads, dry-matcher - pattern matching

Actors in Ruby! Why let Elixir have all the fun by Marcos Matos

Video

• Threads vs. forks (forks heavy - even with CoW optimisations).
• Forking does not have built-in way to communicate - some form of IPC is required, e.g. message queues.
• GIL is not a problem for IO workloads - it is not held during IO (network calls or file reads).
• Core issue is sharing mutable state and managing threads
• Introduction to Celluloid
  • async programming, actors -> OO + message passing
  • message passing, actors mutate their own, isolated state, process messages from mailbox
  • actors - thread based workers
  • managed worker pool
  • supervision of workers, composable to hierarchies
  • linking -> ‘running/dead’ dependency
• Dcell (distributed actors, ZeroMQ)

Defragging Ruby by Aaron Patterson

Video

• Ruby heap layout (pages, slots)
• Memory alignment - objects on 40 byte boundary, pages 16k (407, 408 objects on a page)
• Certain objects do not get allocated on the heap (pointer tagging - alignment frees lower bits for tagging)
• Idea: defragment heap, to free pages after they get fragmented after GC - improve locality, performance. Run GC.compact after app startup, before forking new Unicorn workers.
• ObjectSpace.dump_all + determining page address => heap fragmentation map
• An algorithm to compact heap (two finger compaction, or Cheneys GC algoithm )
• Obstacles (memory address dependent code - e.g. object_id, C extensions).
• Certain pages still cannot get freed, only compacted.
• Solution - keep a hash table of un-relocatable objects. Sounds hacky, maybe no other way to keep backwards-compat?
• Code in a public repo

Performance Optimization in Ruby by Prathmesh Ranaut

Video

• Have a benchmarking suite - benchmark-ips, method_profiler
• Profile methods, find out the bottleneck - memory, CPU, IO bound workload?
• Upgrade MRI Ruby - constant perf improvements in newer versions
• Try multithreading
• Try alternative implementations JRuby, Rubinius - might be better for certain workloads, benchmarks required

Ruby, HTTP2 by Hiro Asari

Video

• Intro to how H2 works
• There’s no proper support in Ruby/Rack yet, apart from a few H2 clients. Rack is solely request/response oriented.