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
Design for Retry (Oneshot Budapest)
Search
Aria Stewart
November 21, 2014
Programming
0
65
Design for Retry (Oneshot Budapest)
Aria Stewart
November 21, 2014
Tweet
Share
More Decks by Aria Stewart
See All by Aria Stewart
Nuts and Bolts of Internationalization
aredridel
0
180
Design for Retry (Nodevember)
aredridel
0
53
Other Decks in Programming
See All in Programming
ソフトウェア品質を数字で捉える技術。事業成長を支えるシステム品質の マネジメント
takuya542
2
14k
ニーリーにおけるプロダクトエンジニア
nealle
0
880
初学者でも今すぐできる、Claude Codeの生産性を10倍上げるTips
s4yuba
16
12k
Hack Claude Code with Claude Code
choplin
5
2.4k
Porting a visionOS App to Android XR
akkeylab
0
640
20250628_非エンジニアがバイブコーディングしてみた
ponponmikankan
0
710
VS Code Update for GitHub Copilot
74th
2
670
Result型で“失敗”を型にするPHPコードの書き方
kajitack
5
970
dbt民主化とLLMによる開発ブースト ~ AI Readyな分析サイクルを目指して ~
yoshyum
3
1.1k
PHP 8.4の新機能「プロパティフック」から学ぶオブジェクト指向設計とリスコフの置換原則
kentaroutakeda
2
990
ご注文の差分はこちらですか? 〜 AWS CDK のいろいろな差分検出と安全なデプロイ
konokenj
3
370
チームのテスト力を総合的に鍛えて品質、スピード、レジリエンスを共立させる/Testing approach that improves quality, speed, and resilience
goyoki
5
990
Featured
See All Featured
How to Create Impact in a Changing Tech Landscape [PerfNow 2023]
tammyeverts
53
2.9k
Large-scale JavaScript Application Architecture
addyosmani
512
110k
Into the Great Unknown - MozCon
thekraken
40
1.9k
Building Better People: How to give real-time feedback that sticks.
wjessup
367
19k
Performance Is Good for Brains [We Love Speed 2024]
tammyeverts
10
970
Facilitating Awesome Meetings
lara
54
6.5k
Designing for Performance
lara
610
69k
Docker and Python
trallard
44
3.5k
Code Reviewing Like a Champion
maltzj
524
40k
Thoughts on Productivity
jonyablonski
69
4.7k
No one is an island. Learnings from fostering a developers community.
thoeni
21
3.4k
Faster Mobile Websites
deanohume
307
31k
Transcript
Design for Retry: Microservices, REST, and why Idempotency is the
only way to scale I'm Aria Stewart, that's @aredridel just about everywhere. I'm here thanks to PayPal. I work on the open source Kraken.js framework.
I'm going to talk about errors. It's going to be
okay.
if (err) { alert(err.message); } else { doMyThing(); }
We all know HTTP
2xx OK 3xx Go elsewhere 4xx Tell user what they
did wrong 5xx Bail out and log an error I'd call this Error avoidance
You can't avoid errors
Here's the secret Handle errors instead
4xx Tell the user what they did wrong 5xx Save
that request and do something with it later.
Retry it 5xx are errors the requestor can handle
But you can't just do things twice? We must make
operations idempotent
Idempotency Repeated actions have no effect, give the same result
This means being smart about IDs. Don't recycle! Check if things are already done. They are? Just give the same answer again.
Causes! —database down —bug in a service —Deploy in progress
—power failure —kicked a cable —Network congestion —Capacity exceeded —Microbursts
—Tree fell on the data center —earthquake —tornado —birds, snakes
and aeroplanes —Black Friday —Slashdot effect —Interns —QA tests —DoS attack
You need a queue
Lots of ways to do it Database on each node.
Maybe LevelDB? Log file Queue server
gearman Queues built in There are many alternatives, but gearmand
is very simple. The memcache of job queues.
Three statuses: —OK (Like 200) —FAIL (Like 400) —ERROR (Like
500)
design so ERROR can be retried.
gearmand automatically tries a job ERROR again. And again. And
again.
If it isn't sure it worked? Tries it again.
You cannot know if an error is a failure.
Error handling gets simpler —Exception? ERROR. —Database down? ERROR. —Downstream
service timeout? ERROR. Maybe you retry right away.
How many of you have used a job queue?
You have used a job queue
Let me tell you about one TRILLIONS of messages MILLIONS
of nodes 100% availability (at least partial) for years. 32 years. Resilient to MILLIONS of bad actors. It is attached to the most malicious network.
EMAIL. 250 OK 4xx RETRY 5xx Fail
Responsibility for messages 250 - accept responsibility 4xx - reject
responsibility 5xx - return responsibility
reject responsibility. If there's an error? Fail fast. The requester
can retry.
Fail fast. Queue work you can't reject. Reject everything you
can if there is an error.
You need a smart client. Keeps outstanding requests. Resubmit. Try
a different server! Try a second queue service. Maybe have a fallback plan.
Smart Clients on the device Toto, we're not in AWS
anymore.
Ever lose an email because you've been logged out?
Latency + Mutable state = Distributed system CAP Theorem Applies!
C = Consistency If there's state that one part knows
of that another doesn't? That's inconsistency.
Job queues are controlled inconsistency.
Ever try to write email on the web while not
on the Internet? It's cloud easy!
This is really good for offline-first design! Being offline is
the ultimate retriable error.
Some ideas
Use your queue as a place to measure for system
sizing
Queue things in localStorage
Use third-party storage
Integrate third-party services with this approach.
Use different strategies for available resources vs contended
Thank you! I hope you have lots of ideas queued
up. Save your ideas and unspool them onto Twitter when you get home. Let me know if this changed how you think about designing applications!