"walk in a distributed systems park with orleans" Евгений Бобров

Walk in a distributed systems park with Orleans

Yevhen Bobrovyevhen

YouScan.io@

Orleans is …

… runtime and programming model for building distributed systems based on actor model

Built by eXtreme Computing Group at Microsoft Research

Has been used internally (during last few years)

Open-sourced in 2015(available on GitHub and Nuget)

ScalabilityAvailabilityReliablity

built for *

HALO4

Orleanspowered by

11+ million players1.5 billion games270 million hours

Why do we need it?

Stateless Services

Service

Stateless Services

ServiceService

Stateless Services

ServiceService Service

Service

Service

Service

Data Shipping Paradigm

Stateless Services (a.k.a 3-tier)scales very badly

In a Cloudlatency will kill you

Stateful Services

Service

Service

Service

Function Shipping Paradigm

Stateful Services

Stateful Services

shared state

Stateful Services

shared stateconcurrency, locks, and all that jazz

Stateful Services

shared stateconcurrency, locks, and all that jazz

PAIN

Actor Model

Single-threaded execution (no need to use locks)

Data locality and consistency (due to encapsulation)

Objects on steroids

Stateful Services

Actors make it simple

How to distribute?

Akka / Erlang

10.0.0.1

10.0.0.2

var game = activate(“game”, “tcp://10.0.0.1”)game.invoke(“foo()”)

var user = activate(“user”, “tcp://10.0.0.2”)user.invoke(“bar()”)

Routing Problems

10.0.0.1

10.0.0.2

10.0.0.5

10.0.0.8

Routing Problems

Cluster Membership

Routing Problems

Cluster Membership Workload Distribution

Routing Problems


Static

Routing Problems


StaticDynamic

Routing Problems


StaticDynamic Distributed Consensus

Routing Problems



Timeouts

Routing Problems



TimeoutsLifecycle

Routing Problems



TimeoutsLifecycle

PAIN

Orleans is …

… runtime and programming model for building distributed systems based on actor model

ScalabilityAvailabilityReliablity

How?

Virtual Actors

Location Transparency


Akka / Erlang

Orleansvar game = activate(“game”) “tcp://10.0.0.1”)game.invoke(“foo()”)

Perpetual Existence


Akka / Erlang

Orleansvar game = activate(“game”, “tcp://10.0.0.1”)game.invoke(“foo()”)

inversion of control

• Placement• Lifecycle

Runtime takes care of

New node joined the

cluster

Unavailable (crashed)

node

New Activation New actor activations

courtesy of @johnazariah

Cooperative multitasking

Threads ~= Cores

Core 1

Core 2

Core N

Mechanical sympathy

Scheduler(turns)

Thread 1

Thread N

Non-blocking IOPromises (TPL, Task, Combinators)

Multiplexed TCPMillions of actors with low OS overhead

Automatic backpressure by designSynchronous, request-response messaging

Tour De Orleans

Grain(a.k.a. Actor)

Silo(a.k.a. Node)

Cluster(a.k.a. Cluster)

Major Concepts

Define interface:

public interface IInventoryItemGrain : IGrain { Task Increment(int qty); Task Decrement(int qty); Task<int> Total(); }

Define implementation:class InventoryItemGrain : Grain, IInventoryItemGrain{ int total;

public Task Increment(int qty) { total++; return TaskDone.Done; }

public Task Decrement(int qty) { total--; return TaskDone.Done; }

public Task<int> Total() => Task.FromResult(total);}

Invoke:

var item = GrainFactory .GetGrain<IInventoryItemGrain>("iPhone");

await item.Increment(100);await item.Decrement(100);

Console.WriteLine(await item.Total());

More Orleans

Placement hints

• Random (default)

• Prefer-local (clustering actors)

• Distribute evenly (# of activations)

Automatic deactivation(garbage collection)

• Global timeout (idle time)

• Per-actor type

• Imperative deactivation

Timers/Reminders

• Async timers (single-threaded guarantee)

• Durable recurrent reminders

retries, recurrent tasks

Streams

• Direct TCP / Azure Queues

• Durable Pub-Sub (WATS/SQL)

• Declarative subscriptions

• Cluster-wide

When to use?

Scaling 3-tier architecture(stateless services)

IoT1. GPS Tracker (RFID, inventory, cars)2. Counters (running total)3. Sensor data

Data stream processing1. Fraud detection2. Aggregation

Ultra-scalable & reliable web crawling

"walk in a distributed systems park with orleans" Евгений Бобров

Technology