RubyConf 2014 - Day 2

Keynote - Sandi Metz - MADAM SANDI TELLS YOUR FUTURE

• Matz is nice and so we are nice (minaswan)
• Scroll -3000 to 0
• Romans - Codex (books) - random access. read and write at the same time
• Scriptorium - snarky comments -
• 0 to 1400 - written by hand
• 1450 - gutenberg
  • yak shaving - letter print (swort?) - wear out quickly
  • need reliable way to copy sworts
  • lost the rights
  • print shops
    • upper case and lower case
    • stereotypes - whole pages cast instead of just the individual letters
  • still set by hand. newspapers have to do it every day
• 18x linotype
  • dynamicly cast a whole line of type
  • machine to create lines of type, molds lead after lining up
  • edison called 8th wonder of the world
  • newspapers 8 to 48 pages per issue
  • newspapers actively recruited deaf employees
  • never complain about CSS again
  • worldwide literacy
• hot to cold type
• the fortune : everything will change
  • death, decay, obscelence
  • the ‘happy path’ of life
  • MVP - health, happyness
  • contribute
  • do for others
  • always something that needs doing

Fringe Ruby - 2 + CATS = 4 * CUTE: HOW MATH WORKS IN RUBY - Chris Hoffman - @yarmiganosca - Optoro

• numerical coercion
• #coerce(numeric) -> array - find a common type between the two operands
  • 1.2.coerce(3) => [3.0, 1.2]
• Vectors - can we make these work with coerce?
  • yes, define coerce and operation(s)
• Dimensional analysis
  • gem unitary
  • size * dimension
• Other uses
  • currency manipulation (gem conversions)
  • balance chemical equations?
  • function scaling/composition

Fringe Ruby - A PARTIAL-MULTIVERSE MODEL OF TIME TRAVEL FOR DEBUGGING - Brock Wilcox

• pry-byebug (2.0+)
• YARV bytecode
  • trace codes - hooks into VM state
• pry-timetravel
  • back to step backwards into previous state
• every next, fork and suspend the fork
• back, grab most recent child fork
• pid = fork
  • if pid parent; else child
  • $$ = current pid
• signals (OS Callbacks)
  • Signal.trap
  • Process.kill
  • SIGTSTP - SIGSTOP (uncatchable) - no io, etc, -> SIGCONT (continue, unstop)
• limitations
  • can only go back as far as snapshots
  • shared file handles, incl sockets
  • threads :-( - no copy of threads
  • memory exhaustion
• complication
  • shell detects stop, inside
    • fix : make dummy parent process
  • killing parent processes
    • fix : kill the others
    • except everything will have this, so force? Kernel.exit!
  • zombies
    • child exited, but parent doesnt waitpid - process is dead, yet remains
    • owned by init
• snapshot tree?
  • can back to pid
• ‘snap $cmd’
• autosnapshot and prune
  • autosnap every stack frame change
• other techniques
  • yarv - keep track of everything there
  • ocaml debugger does fork()
  • “why is reverse debugging rarely used” on stackexchange
  • elm-lang, watches what is changed

JRuby 9000 - Charles Nutter @headius & Tom Enebo @tom_enebo

• Ruby on JVM
  • native threads, tooling, JIT
  • pull in any java library, ehcache, neo4j, lucene
  • other languages, scala, jython, clojure, groovy
• JRuby 1.7 == Ruby 1.8 or 1.9 - new releases frequently
• JRuby 9 == Ruby 2.2(+) - release mid Jan?
  • New runtime
  • Major IO & Encoding
• timing
  • startup time (from command line)
  • warmup time (until best performance)
  • running time (now running)
• indy (invoke dynamic) - high warmup time, lower stable time
• MRI - internal representation -> interpreter
• Jruby - internal representation -> (interpreter) -> java bytecode -> native code
• why not JIT everything? cause warmup is slow.
  • JIT creates lots of classes
  • more code for the JVM to deal with
• benchmarking
  • benchmark/ips or perfer
  • with warmup/rehearsal time
• jvm and jruby are mixed mode - interpreter -> JIT
• example
• deoptimization (undo optimizations) to try crazy optimizations and rollback if it doesnt work
• Jruby –dev (skip jit) faster warmup for dev
• Drip - new jvm for next command, like spring preloader
  • tell what to preboot, gets faster
• New runtime (IR)
  • no AST, semantic representation
  • traditional compiler design
  • no heap allocated arguments, removes extra binding
  • add jruby –debug
  • compiler optimizations (dead code, constant propogation, inlining, unboxing) - done with pluggable compiler passes
• new IO and character Transcoding (M17n)
  • MRI gives thin wrapper around fd
  • JVM gives Channel, which looks like fd
  • old Jruby emulates libc fd
  • JDK uses UTF16
  • impossible to emulate some POSIX stuff
  • new IO layer (OpenFile) - passes nearly all, performance better, match MRI
• Old JIT
  • 16k loc just for bytecode gen
  • one-off optimizations
• New JIT
  • 95% done
  • 56k loc
  • equal performance, lots of room to improve
• Memory Analysis + debugging
  • VisualVM. GC, java object level
  • Ruby-centric version
  • Alienist - java -> ruby heap dump
    • mri version?
    • size, query language?
    • allow implementation specific data
    • spec for json format
• TODOs
  • finish JIT
  • AOT compiler (jrubyc)
  • IR compile & interp speedups
  • Refinements
  • MRI test suite
• How to help
  • run master - jruby-head (in travisci)
  • openjdk8 oraclejdk8 openjdk7
  • rbenv/ruby-build jruby-9(.0.0.0)-dev
  • setup for dev - clone; mvn -Pbootstrap;
  • run tests/specs, find excluded that is fixed
  • fork, create a branch, send a PR
    • implement tagged/excluded
    • mine for bugs (Beginner tags)

Elixr

• Thread - lots of ways to shoot self in foot
• Built on Erland VM - Erricson labs - telephone switch
• Not just a CoffeeScript for Erlang
• better tools, syntax, standardlib
• Tools
  • iex (REPL) - built in doc system, in markdown
  • mix (project mgr, create project, manage dependencies, run tests)
• pipe operator
  • data transformations - (nested fns)
• Actor concurrency model
  • “Process”
  • performs one task
  • send and receipt messages, messages are pattern matched to methods
  • unshared memory
  • Ackermann function
  • unprocessed messages are buffered (queued)
• Fault tolerance
  • supervision tree. supervisors are just processes
  • can restart processes, kill them off etc
  • keep calm and let it crash
  • supervisor heirarchy can take over and put system back together
• http load tester example
  • coordinator, create workers, track responses
  • workers just send message back with result
• task is like a future/promise
  • runs in a container. await to gather result
• distributed
  • message passing between processes on network are transparent
• Phoenix Framework

MY LITTLE C EXTENSION: LEGO ROBOTS ARE MAGIC - Brandon Hays

• about burnout
• how to C in ruby
  • start a gem, good guide on rubygems
  • include ruby.h
  • include c dependencies
  • magic Init_native to define module, method(s)
  • cast C types to Ruby types
  • (VALUE self) - own ruby object
  • segfaults (yay)
• wrap the rest of the API
• Style Guide
  • Keep low level like C (ugly)
  • Low level wrappers in a ::Native module
  • prefix c method helpers
• C Ext Cheat sheets (links in slides)
• atone for cheating :-)
• oh no, people are using it
• how did it help burnout?
  • just doing something for self
  • play to get <3 back
  • play is how you realize unlimited potential