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
99
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
350
Reliable High-Performance HTTP Infrastructure with nginx and Lua
seancribbs
0
580
The Refreshingly Rewarding Realm of Research Papers
seancribbs
0
370
Roll-your-own API Management Platform with NGINX and Lua
seancribbs
10
1.1k
Techniques for Metaprogramming in Erlang
seancribbs
2
1.4k
The Final Causal Frontier
seancribbs
6
920
Erlang - Building Blocks for Global Distributed Systems
seancribbs
4
830
A Brief History of Time in Riak
seancribbs
4
1.8k
Other Decks in Technology
See All in Technology
React ABC Questions
hirotomoyamada
0
490
AWS Control Towerを 数年運用してきての気づきとこれから/aws-controltower-ops-tips
tadayukinakamura
0
160
DuckDB MCPサーバーを使ってAWSコストを分析させてみた / AWS cost analysis with DuckDB MCP server
masahirokawahara
0
1.3k
コスト最適重視でAurora PostgreSQLのログ分析基盤を作ってみた #jawsug_tokyo
non97
0
420
AIエージェント開発手法と業務導入のプラクティス
ykosaka
2
1.5k
SDカードフォレンジック
su3158
1
630
MCPを活用した検索システムの作り方/How to implement search systems with MCP #catalks
quiver
12
6.8k
Porting PicoRuby to Another Microcontroller: ESP32
yuuu
4
440
品質文化を支える小さいクロスファンクショナルなチーム / Cross-functional teams fostering quality culture
toma_sm
0
120
SREからゼロイチプロダクト開発へ ー越境する打席の立ち方と期待への応え方ー / Product Engineering Night #8
itkq
2
930
AIでめっちゃ便利になったけど、結局みんなで学ぶよねっていう話
kakehashi
PRO
0
180
AWSの新機能検証をやる時こそ、Amazon Qでプロンプトエンジニアリングを駆使しよう
duelist2020jp
1
260
Featured
See All Featured
Done Done
chrislema
183
16k
Evolution of real-time – Irina Nazarova, EuRuKo, 2024
irinanazarova
8
670
Navigating Team Friction
lara
184
15k
For a Future-Friendly Web
brad_frost
176
9.7k
How to Think Like a Performance Engineer
csswizardry
23
1.5k
Docker and Python
trallard
44
3.3k
Git: the NoSQL Database
bkeepers
PRO
430
65k
The Psychology of Web Performance [Beyond Tellerrand 2023]
tammyeverts
47
2.7k
Stop Working from a Prison Cell
hatefulcrawdad
268
20k
The MySQL Ecosystem @ GitHub 2015
samlambert
251
12k
Sharpening the Axe: The Primacy of Toolmaking
bcantrill
41
2.2k
It's Worth the Effort
3n
184
28k
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