Osdc 2011 michael_neale
- 2. @michaelneale github.com/michaelneale currently: trying to make less reliable things more reliable.
- 3. Some things we use to get it done: - scala (back end apps) - ruby (chef, rails, proxymachine, lots) - java (jenkins and plugins) - erlang (āagentsā and lots more..)
- 4. Exceptions. Errors. What The Hell Is That Process Doing? and how it relates to..
- 5. On Call PTSD
- 6. Exception handling is wrong...
- 7. But it seems harmless...
- 10. Erlang says no no no...
- 11. Question: a process on server not responding Answer: 1) panic 2) take time thinking about underlying cause 3) bounce the bastard and pray **
- 12. FACT: Answer#3 will often work so well, you often donāt really spend time to think about doing #2** ** FibreError?
- 14. Imagine a programming environment: - unlimited process spawning - concurrency someone elseās problem - donāt try to handle errors - let it fail
- 15. Erlang Built for stability, and not bothering me. Anything else is gravy I wasnāt an erlang programmer
- 16. Process isolation - it works so well - nothing shared - has worked so well for so long with OSes - in erlang - each āprocessā is like a process !
- 17. nginx Example: My Host OS haproxy Erlang process supervisor ... p1 p999 Each: own heap, garbage collector
- 18. Erlang is: - A vm based runtime (light !) - language with prolog heritage (!) - compiler - interpreter - debug tools - batteries included - OTP - an application (server?) platform
- 19. Erlang is: - Not OO - no shared state ** - state kept in āterm storesā - mini DBs - processes easy to hot swap - Quasi functional programming (immutable variables, higher order) - distributed (if you want)
- 23. OTP - Open Telecommunications Platform - not about telco ! - network stacks/apis, supervisor trees - toolkit for reliable servers (middleware) - behaviours
- 27. State in erlang ļ¬les Host + real kernel Erlang process DETS supervisor ... ETS p1 p999 Send Receive
- 28. Erlang processes, like OS processes - Can only send messages to each other - Can fail independently - Can be restarted, safely, independently - Easy to write apps for - Old School !
- 29. Better - Tiny overhead (can have 100K+ of them !) - perfect for supervisory agents - distribute: run on every box if you like ! - lots of processes == lots of concurrency - if you need to block, block !
- 30. Have used erlang for - Supervisory agents - controllers - Autoscaling services (realtime data analytics) - misc backend systems - fun command line tools ! - is āliteā VM (startup, footprint)
- 31. Supervisor conļ¬guration - Declare rules for restarting, failure - So you donāt have to intervene ! - can hot reload changes - can have dependent processes
- 32. Restart just busted process
- 33. Program 1 (module with behaviour)
- 34. Program 2 (module with behaviour)
- 35. Anyway, that is why we use Erlang, also... - RabbitMQ - Riak (nosql DB) - CouchDB (nosql DB) - Probably your telephone exchange
- 36. Alternative approaches: - Use ānativeā with daemontools/monit etc - Akka (Scala) has similar supervisor - library for your favourite language - ephemeral āstate lessā apps - Write software without bugs - Or just restart everything 400 times a day
- 37. What is not awesome: - OTP boiler plate - VM not as fast as some - No one seems to like the language - tools? IDEs?
- 38. Thank you