scaling unstable systems velocity 2015
TRANSCRIPT
Systems ThinkingPatterns for scaling unstable systems
@_siddharth_ram
Siddharth Ram Chief Architect, Small Business Group
Intuit
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About QuickBooks
Unskilled and Unaware of It:
How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessments
The Dunning-Kruger Effect
3. Hofstadter’s lawIt always takes longer than you expect, even when you take into account Hofstadter’s law
5. The End to End Principle
http://web.mit.edu/Saltzer/www/publications/endtoend/endtoend.pdf
Reliability from unreliable parts
Everything always works
I do my job. Others need to do theirs
Everything is broken
My service works even when my dependent services are broken
Blind Faith
Trust but verify
Infrastructure is broken
Software is broken
My service works when there are infrastructure
problems
My Service works even when my hardware &
software dependencies are broken
God’s country
Dunning-KrugerOptimism bias
Circuit Breakers Destructive Testing
Fallacies of Distributed computing
The network is reliable
• Transport cost is zero
• It is easy to coordinate nodes in a network
• The network is homogenous
• There is one administrator
• Bandwidth is infinite
• Topology does not change
• The network is secure
• Latency is zero
Hofstradter’s law
Horizontal duplication
Serv
ices
Shar
ding
(0,0,0) Monolith
(1,0,0) Read replicas
(0,0,1) Sharding
(0,1,0) Services
(1,1,1) Infinite Scale
C Axis Organizational
Scale
How to
Scale
The rule of least power
Atwoods Law
The less powerful the language, the more you can do with the data stored
in that language
Occam’s Razor Simpler is better
Any application that can be written in JavaScript, will eventually be written in
JavaScript.
4 Tier Applications - add NodeJS
Clients
NodeJS
ClientsClients
Java
Data
Atwoods Law
Useful C
omplexity
Full S
tack
Full S
tack
DevOps - own it end to endYou built it, you run it - https://queue.acm.org/detail.cfm?id=1142065
Giving developers operational responsibilities has greatly enhanced the quality of the services, both from a customer and a technology point of view. The traditional model is that you take your software to the wall that separates development and operations, and throw it over and then forget about it. Not at Amazon. You build it, you run it. This brings developers into contact with the day-to-day operation of their software. It also brings them into day-to-day contact with the customer. This customer feedback loop is essential for improving the quality of the service
– Werner Vogels
State kills. Kill State
Session and state destroy the ultimate value promised by multi-tenancy within Internet (SaaS, commerce, and so on)
applications.
- 50 Principles for Scaling Web Sites
Don’t simplify by creating unnecessary complexity
Kill Stat
e
FacadeFacadeCache
{ X-identity:
X-i18n: X-role:
X-permission:
}HTTP Headers
{ X-identity:
X-i18n: X-role:
X-permission: X-TX-Count:
}
12
3
Roles Permissions
Identity Loos
e Cou
pling
Unreliable, high
throughput
recovery logic
Event SourceMessage
Bus
ConsumersConsumersConsumers
Loos
e Cou
pling