go reactive: building responsive, resilient, elastic & message-driven systems
Post on 21-Apr-2017
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Jonas Bonér CTO Typesafe
@jboner
Go ReactiveBuilding Responsive, Resilient,
Elastic & Message-Driven Systems
The rules of the game
have changed
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Yesterday Today
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Yesterday Today
Single machines Clusters of machines
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Yesterday Today
Single machines Clusters of machines
Single core processors Multicore processors
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Yesterday Today
Single machines Clusters of machines
Single core processors Multicore processors
Expensive RAM Cheap RAM
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Yesterday Today
Single machines Clusters of machines
Single core processors Multicore processors
Expensive RAM Cheap RAM
Expensive disk Cheap disk
3
Yesterday Today
Single machines Clusters of machines
Single core processors Multicore processors
Expensive RAM Cheap RAM
Expensive disk Cheap disk
Slow networks Fast networks
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Yesterday Today
Single machines Clusters of machines
Single core processors Multicore processors
Expensive RAM Cheap RAM
Expensive disk Cheap disk
Slow networks Fast networks
Few concurrent users Lots of concurrent users
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Yesterday Today
Single machines Clusters of machines
Single core processors Multicore processors
Expensive RAM Cheap RAM
Expensive disk Cheap disk
Slow networks Fast networks
Few concurrent users Lots of concurrent users
Small data sets Large data sets
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Yesterday Today
Single machines Clusters of machines
Single core processors Multicore processors
Expensive RAM Cheap RAM
Expensive disk Cheap disk
Slow networks Fast networks
Few concurrent users Lots of concurrent users
Small data sets Large data sets
Latency in seconds Latency in milliseconds
Reactive “Readily responsive to a stimulus”
- Merriam Webster
Reactive Applications
The Principles of Reactive Systems
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Responsive “Quick to respond or react appropriately”
- Merriam Webster
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The system should always be responsive
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1. Blue skies2. Heavy load3. Failures
The system should always be responsive
Resilient “The ability of a substance or object to spring back into shape”
“The capacity to recover quickly from difficulties” - Merriam Webster
Think Vending Machine
Coffee Machine
Programmer
Think Vending Machine
Coffee Machine
Programmer
Inserts coins
Think Vending Machine
Coffee Machine
Programmer
Inserts coins
Add more coins
Think Vending Machine
Coffee Machine
Programmer
Inserts coins
Gets coffee
Add more coins
Think Vending Machine
Coffee Machine
Programmer
Think Vending Machine
Coffee Machine
Programmer
Inserts coins
Think Vending Machine
Coffee Machine
Programmer
Inserts coins
Think Vending Machine
Out of coffee beans error
Coffee Machine
Programmer
Inserts coins
Think Vending Machine
Out of coffee beans error
WRONG
Coffee Machine
Programmer
Inserts coins
Think Vending Machine
Coffee Machine
Programmer
Inserts coins
Out of coffee beans
failure
Think Vending Machine
Coffee Machine
Programmer
Service Guy
Inserts coins
Out of coffee beans
failure
Think Vending Machine
Coffee Machine
Programmer
Service Guy
Inserts coins
Out of coffee beans
failure
Adds more beans
Think Vending Machine
Coffee Machine
Programmer
Service Guy
Inserts coins
Gets coffee
Out of coffee beans
failure
Adds more beans
Think Vending Machine
The Right Way
ServiceClient
The Right Way
ServiceClient
Request
The Right Way
ServiceClient
Request
Response
The Right Way
ServiceClient
Request
Response
Validation Error
The Right Way
ServiceClient
Request
Response
Validation Error
Application Failure
The Right Way
ServiceClient
Supervisor
Request
Response
Validation Error
Application Failure
The Right Way
ServiceClient
Supervisor
Request
Response
Validation Error
Application Failure
Manages Failure
Resilience IsBy Design
1. Isolate the failure
2. Compartmentalize
3. Manage failure locally
4. Avoid cascading failures
Use Bulkheads
1. Isolate the failure
2. Compartmentalize
3. Manage failure locally
4. Avoid cascading failures
Use Bulkheads
Enter Supervision
A
B
BarFoo
C
BE
A
D
C
Automatic and mandatory supervisionSupervisor hierarchies
A
B
BarFoo
C
E
A
D
C
Automatic and mandatory supervisionSupervisor hierarchies
B
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Every single actor has a default supervisor strategy. Which is usually sufficient. But it can be overridden.
Supervision in Akka
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class Supervisor extends AbstractActor { private SupervisorStrategy strategy = new OneForOneStrategy( 10, Duration.create(1, TimeUnit.MINUTES), DirectiveBuilder. match(ArithmeticException.class, e -> resume()). match(NullPointerException.class, e -> restart()). matchAny( e -> escalate()). build()); … // rest of actor omitted
} }
Supervision in Akka
Resilience requires aMessage-DrivenArchitecture
Elastic “Capable of ready change or easy expansion or contraction”
- Merriam Webster
UPScale
UPScale
and down
1. Minimize Contention 2. Maximize Locality of Reference
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We need to
Common points of
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ApplicationPhysical
contention
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GO
Async
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GO
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Neverever
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Neverever
Block
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Neverever
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NOTHINGshare
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Needs to be async and non-blocking all the way down…
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Needs to be async and non-blocking all the way down…
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Single Writer Principle
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Single Writer PrincipleIO deviceProducers
SERIAL & CONTENDED
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Single Writer PrincipleIO deviceProducers
SERIAL & CONTENDED
IO deviceProducers Actor or Queue
BATCHED & UNCONTENDED
The Role of Immutable State
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The Role of Immutable State
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The Role of Immutable State• Great to represent facts • Messages and Events
• Database snapshots
• Representing the succession of time
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The Role of Immutable State• Great to represent facts • Messages and Events
• Database snapshots
• Representing the succession of time
• Mutable State is ok if local and contained • Allows Single-threaded processing
• Allows single writer principle
• Feels more natural
• Publish the results to the world as Immutable State
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Divide & Conquer
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Pipelining
ON DEMAND
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scale
OUTScale
OUTScale
and in
• Mobile
• Cloud Services, REST etc.
• NOSQL DBs
• Big Data
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Distributed Computing is the
new normal
What is the essence of distributed systems?
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What is the essence of distributed systems?
To try to overcome that1. Information travels at the speed of light
2. Independent things fail independently
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Slow node
Dead node
No difference
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and a
Between a
The network is
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The network is
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http://aphyr.com/posts/288-the-network-is-reliable
Inherently Unreliable
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Graveyard of distributed systems
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Graveyard of distributed systems• Distributed Shared Mutable State
• EVIL (where N is number of nodes)N
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Graveyard of distributed systems• Distributed Shared Mutable State
• EVIL (where N is number of nodes)N
• Serializable Distributed Transactions
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Graveyard of distributed systems• Distributed Shared Mutable State
• EVIL (where N is number of nodes)N
• Serializable Distributed Transactions
• Synchronous RPC
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Graveyard of distributed systems• Distributed Shared Mutable State
• EVIL (where N is number of nodes)N
• Serializable Distributed Transactions
• Synchronous RPC
• Guaranteed Delivery
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Graveyard of distributed systems• Distributed Shared Mutable State
• EVIL (where N is number of nodes)N
• Serializable Distributed Transactions
• Synchronous RPC
• Guaranteed Delivery
• Distributed Objects
• “Sucks like an inverted hurricane” - Martin Fowler
Instead
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Embrace the Network
Instead
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and be d
one with itUse
Asynchronous Message Passing
TRANSPARENCY
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location
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Scaling Up and Out is essentially
the same thing
Elasticity requires aMessage-DrivenArchitecture
AsynchronousMessage-Passingis the enabler
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Typesafe Reactive Platform
• Actors are lightweight, isolated and and communicate via asynchronous message passing
• Supervision and clustering in support of fault tolerance
• Purely asynchronous and non-blocking web framework
• No container required, no inherent bottlenecks in session management
• Asynchronous and immutable programming constructs
• Composable abstractions enabling simpler concurrency and parallelism
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Finance Internet/Social Media Mfg/Hardware Government Retail
Jonas Bonér CTO Typesafe
@jboner
Go ReactiveBuilding Responsive, Resilient,
Elastic & Message-Driven Systems
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