Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Supervisors, Links and Monitors
Search
Sean Cribbs
September 20, 2016
Technology
0
110
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
380
Getting the Word Out: Membership, Dissemination, and Population Protocols
seancribbs
0
360
Reliable High-Performance HTTP Infrastructure with nginx and Lua
seancribbs
0
600
The Refreshingly Rewarding Realm of Research Papers
seancribbs
0
380
Roll-your-own API Management Platform with NGINX and Lua
seancribbs
10
1.1k
Techniques for Metaprogramming in Erlang
seancribbs
2
1.5k
The Final Causal Frontier
seancribbs
6
920
Erlang - Building Blocks for Global Distributed Systems
seancribbs
4
840
A Brief History of Time in Riak
seancribbs
4
1.8k
Other Decks in Technology
See All in Technology
VPC Latticeのサービスエンドポイント機能を使用した複数VPCアクセス
duelist2020jp
0
220
AIドリブンのソフトウェア開発 - うまいやり方とまずいやり方
okdt
PRO
9
580
人を動かすことについて考える
ichimichi
2
320
モバイルアプリ研修
recruitengineers
PRO
2
250
制約理論(ToC)入門
recruitengineers
PRO
2
290
トヨタ生産方式(TPS)入門
recruitengineers
PRO
2
220
AIエージェント就活入門 - MCPが履歴書になる未来
eltociear
0
490
ECS モニタリング手法大整理
yendoooo
1
120
Oracle Base Database Service:サービス概要のご紹介
oracle4engineer
PRO
2
20k
認知戦の理解と、市民としての対抗策
hogehuga
0
320
サービスロボット最前線:ugoが挑むPhysical AI活用
kmatsuiugo
0
190
JavaScript 研修
recruitengineers
PRO
2
160
Featured
See All Featured
BBQ
matthewcrist
89
9.8k
ReactJS: Keep Simple. Everything can be a component!
pedronauck
667
120k
Rebuilding a faster, lazier Slack
samanthasiow
83
9.1k
Build The Right Thing And Hit Your Dates
maggiecrowley
37
2.8k
Bootstrapping a Software Product
garrettdimon
PRO
307
110k
The Illustrated Children's Guide to Kubernetes
chrisshort
48
50k
VelocityConf: Rendering Performance Case Studies
addyosmani
332
24k
Learning to Love Humans: Emotional Interface Design
aarron
273
40k
Improving Core Web Vitals using Speculation Rules API
sergeychernyshev
18
1.1k
Responsive Adventures: Dirty Tricks From The Dark Corners of Front-End
smashingmag
251
21k
Thoughts on Productivity
jonyablonski
69
4.8k
GraphQLとの向き合い方2022年版
quramy
49
14k
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