Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Speaker Deck
PRO
Sign in
Sign up for free
Supervisors, Links and Monitors
Sean Cribbs
September 20, 2016
Technology
0
51
Supervisors, Links and Monitors
Using OTP tools in your Elixir application for great justice
Sean Cribbs
September 20, 2016
Tweet
Share
More Decks by Sean Cribbs
See All by Sean Cribbs
Adopting Stream Processing for Instrumentation
seancribbs
1
340
Getting the Word Out: Membership, Dissemination, and Population Protocols
seancribbs
0
290
Reliable High-Performance HTTP Infrastructure with nginx and Lua
seancribbs
0
490
The Refreshingly Rewarding Realm of Research Papers
seancribbs
0
330
Roll-your-own API Management Platform with NGINX and Lua
seancribbs
10
990
Techniques for Metaprogramming in Erlang
seancribbs
2
1.2k
The Final Causal Frontier
seancribbs
6
840
Erlang - Building Blocks for Global Distributed Systems
seancribbs
4
630
A Brief History of Time in Riak
seancribbs
4
1.2k
Other Decks in Technology
See All in Technology
EKSの運用あれこれ バージョンアップ編
tetsunosato
0
100
20220622_FinJAWS_あのときにAWSがあったらこうできた
taketakekaho
0
120
FastConnect 冗長性のベスト・プラクティス
ocise
0
130
What's new in Vision
satotakeshi
0
220
MRTK3 - DataBinding and Theming 入門
futo23
0
200
The Fractal Geometry of Software Design
vladikk
1
1.3k
eBPF for Security Observability
lizrice
0
220
JAWS-UG re:Habilitaion 報告 / JAWS-UG OITA rehabilitation
hiranofumio
0
130
モブに早く慣れたい人のためのガイド / A Guide to Getting Started Quickly with Mob Programming
cybozuinsideout
PRO
2
1.9k
【Pythonデータ分析勉強会#33】「DearPyGuiに入門しました」の続き~Image-Processing-Node-Editor~
kazuhitotakahashi
0
180
サイボウズの アジャイル・クオリティ / Agile Quality at Cybozu
cybozuinsideout
PRO
4
2.5k
プログラマがオブジェクト指向しても幸せになれない理由
shirayanagiryuji
0
160
Featured
See All Featured
Art Directing for the Web. Five minutes with CSS Template Areas
malarkey
196
9.4k
ピンチをチャンスに:未来をつくるプロダクトロードマップ #pmconf2020
aki_i
23
15k
For a Future-Friendly Web
brad_frost
166
7.4k
Web Components: a chance to create the future
zenorocha
303
40k
Designing with Data
zakiwarfel
91
3.9k
The Invisible Side of Design
smashingmag
290
48k
Large-scale JavaScript Application Architecture
addyosmani
499
110k
Raft: Consensus for Rubyists
vanstee
126
5.5k
How To Stay Up To Date on Web Technology
chriscoyier
780
250k
Templates, Plugins, & Blocks: Oh My! Creating the theme that thinks of everything
marktimemedia
15
950
A Tale of Four Properties
chriscoyier
149
21k
What the flash - Photography Introduction
edds
62
10k
Transcript
SUPERVISORS, LINKS & MONITORS Sean Cribbs
FLASHBACK: 2008 a more innocent time
PLAYSKOOL: MY FIRST ERLANG twitter client mochiweb handler mnesia
PLAYSKOOL: MY FIRST ERLANG ➤ Twitter API changes? CRASH twitter
client mochiweb handler mnesia
PLAYSKOOL: MY FIRST ERLANG ➤ Twitter API changes? CRASH ➤
Buggy request handler? CRASH twitter client mochiweb handler mnesia
PLAYSKOOL: MY FIRST ERLANG ➤ Twitter API changes? CRASH ➤
Buggy request handler? CRASH ➤ Mnesia acting weird? CRASH twitter client mochiweb handler mnesia
PLAYSKOOL: MY FIRST ERLANG ➤ Twitter API changes? CRASH ➤
Buggy request handler? CRASH ➤ Mnesia acting weird? CRASH twitter client mochiweb handler mnesia RESULT: Unpredictable behavior
SUPERVISORS are not for restarting processes
SUPERVISORS are for structuring your application
HINDSIGHT IS 20/20 twitter client mochiweb handler mnesia my_app (supervisor)
HINDSIGHT IS 20/20 ➤ mnesia as application dependency twitter client
mochiweb handler mnesia my_app (supervisor)
HINDSIGHT IS 20/20 ➤ mnesia as application dependency ➤ Client
and mochiweb handler as children twitter client mochiweb handler mnesia my_app (supervisor)
HINDSIGHT IS 20/20 ➤ mnesia as application dependency ➤ Client
and mochiweb handler as children ➤ Supervisor initializes mnesia tables twitter client mochiweb handler mnesia my_app (supervisor)
HINDSIGHT IS 20/20 ➤ mnesia as application dependency ➤ Client
and mochiweb handler as children ➤ Supervisor initializes mnesia tables twitter client mochiweb handler mnesia RESULT: Reliability my_app (supervisor)
:observer.start()
SUPERVISOR STRATEGIES ➤ :one_for_one ➤ :one_for_all ➤ :rest_for_one ➤ :simple_one_for_one
SUPERVISOR STRATEGIES ➤ :one_for_one ➤ :one_for_all ➤ :rest_for_one ➤ :simple_one_for_one
㱺 Task.Supervisor
SUPERVISORS use links and trap exits
LINKS intertwine fates of two processes
A B
A B Process.link(b)
file_server_2 Port (driver)
file_server_2 Port (driver) shutdown!
file_server_2 Port (driver) shutdown! EXIT close()
None
TRAP EXITS if you need to handle exit signals
TRAP EXITS if you need to handle exit signals Process.flag(:trap_exit,
true)
TRAP EXITS if you need to handle exit signals Process.flag(:trap_exit,
true) {:EXIT, pid, reason}
MONITORS notify of process exit without linking
A B
A B Process.monitor(b)
A B Process.monitor(b) {:DOWN, ref, :process, pid, reason}
A B GENSERVER.CALL/3
A B GENSERVER.CALL/3 ➤ Monitor the target {:ok, ref} =
Process.monitor(b)
A B GENSERVER.CALL/3 ➤ Monitor the target ➤ Send the
message tagged with the monitor reference {:ok, ref} = Process.monitor(b) {:'$gen_call', {a, ref}, :hi}
A B GENSERVER.CALL/3 ➤ Monitor the target ➤ Send the
message tagged with the monitor reference ➤ Receive {:ok, ref} = Process.monitor(b) {:'$gen_call', {a, ref}, :hi}
A B GENSERVER.CALL/3 ➤ Monitor the target ➤ Send the
message tagged with the monitor reference ➤ Receive ➤ {^ref, reply} ⇒ {:ok, reply} {:ok, ref} = Process.monitor(b) {:'$gen_call', {a, ref}, :hi}
A B GENSERVER.CALL/3 ➤ Monitor the target ➤ Send the
message tagged with the monitor reference ➤ Receive ➤ {^ref, reply} ⇒ {:ok, reply} ➤ :DOWN ⇒ exit(reason) {:ok, ref} = Process.monitor(b) {:'$gen_call', {a, ref}, :hi}
A B GENSERVER.CALL/3 ➤ Monitor the target ➤ Send the
message tagged with the monitor reference ➤ Receive ➤ {^ref, reply} ⇒ {:ok, reply} ➤ :DOWN ⇒ exit(reason) ➤ timeout ⇒ exit(:timeout) {:ok, ref} = Process.monitor(b) {:'$gen_call', {a, ref}, :hi}
registry conn sup app sup CUSTOM PROCESS REGISTRY
registry conn sup app sup CUSTOM PROCESS REGISTRY ➤ GOAL:
Lookup or start a connection to another node
registry conn sup app sup CUSTOM PROCESS REGISTRY ➤ GOAL:
Lookup or start a connection to another node ➤ Client (GenServer.call) ⇒ Registry client
registry conn sup app sup CUSTOM PROCESS REGISTRY ➤ GOAL:
Lookup or start a connection to another node ➤ Client (GenServer.call) ⇒ Registry ➤ Registry ⇒ Supervisor.start_child client
registry conn sup app sup CUSTOM PROCESS REGISTRY ➤ GOAL:
Lookup or start a connection to another node ➤ Client (GenServer.call) ⇒ Registry ➤ Registry ⇒ Supervisor.start_child conn client
registry conn sup app sup CUSTOM PROCESS REGISTRY ➤ GOAL:
Lookup or start a connection to another node ➤ Client (GenServer.call) ⇒ Registry ➤ Registry ⇒ Supervisor.start_child ➤ Registry ⇒ monitor connection conn client
registry conn sup app sup CUSTOM PROCESS REGISTRY ➤ GOAL:
Lookup or start a connection to another node ➤ Client (GenServer.call) ⇒ Registry ➤ Registry ⇒ Supervisor.start_child ➤ Registry ⇒ monitor connection ➤ Client ⇐ connection pid (maybe monitor?) conn client
registry conn sup app sup CUSTOM PROCESS REGISTRY ➤ GOAL:
Lookup or start a connection to another node ➤ Client (GenServer.call) ⇒ Registry ➤ Registry ⇒ Supervisor.start_child ➤ Registry ⇒ monitor connection ➤ Client ⇐ connection pid (maybe monitor?) ➤ DOWN ⇒ Registry cleans up client
TIPS AND TRICKS ➤ Don’t put too much on your
Supervisor ➤ Child order matters ➤ Use links and monitors ➤ Read the Elixir and Erlang source
REFERENCES ➤ Erlang Reference Manual: Processes http://erlang.org/doc/reference_manual/processes.html ➤ Erlang Reference
Manual: Errors http://erlang.org/doc/reference_manual/errors.html ➤ OTP Design Principles: Overview http://erlang.org/doc/design_principles/des_princ.html ➤ OTP Design Principles: Supervisors http://erlang.org/doc/design_principles/sup_princ.html ➤ OTP Design Principles: Applications http://erlang.org/doc/design_principles/applications.html