WebObjects + Scala Building Concurrent WebObjects applications with - - PowerPoint PPT Presentation

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WebObjects + Scala Building Concurrent WebObjects applications with - - PowerPoint PPT Presentation

Oct 15, 2022 424 likes •1.25k views

WebObjects + Scala Building Concurrent WebObjects applications with Scala Ravi Mendis Why Concurrent Programming? 2005 The year of Dual Core 2010 Today Entry-Level Cores Threads AMD Opteron 4 4 IBM Power7 4 16 Intel Xeon 4 8

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WebObjects + Scala

Building Concurrent WebObjects applications with Scala Ravi Mendis

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Why Concurrent Programming?

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2005

The year of Dual Core

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2010

Today

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Entry-Level

Cores Threads AMD Opteron IBM Power7 Intel Xeon

4 4 4 16 4 8

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High-End

Cores Threads AMD Opteron IBM Power7 Intel Xeon

12 12 8 32 6 12

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2011

Tomorrow

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Roadmap

Cores Threads AMD Opteron IBM Power7 Intel Xeon

16 16 ? ?? 8 16

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“By 2015 we will likely have over 100 cores on a many- core processing chip in our notebook computers.”

  • Computerworld
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Welcome to the world of Multi-cores!

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Q: How do we take advantage of multi-core processors?

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A: Concurrent Programming

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#1 Threads & Locks

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“Concurrency is hard. It involves a lot of problems that are very difficult to think about and reason about and understand”

  • Tim Bray co-inventor of XML
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#1 Threads & Locks

  • HARD to program
  • HARD to scale
  • Contentious
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java.lang.IllegalArgumentException: Cannot determine primary key for entity ASCCarveout from row: {charge = 3027.00; claimID = 321839138; }

  • at com.webobjects.eoaccess.EODatabaseChannel._fetchObject(EODatabaseChannel.java:348)
  • at com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEditingContext

(EODatabaseContext.java:3071)

  • at com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(EODatabaseContext.java:3195)
  • at com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:

488)

  • at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4069)
  • at er.extensions.eof.ERXEC.objectsWithFetchSpecification(ERXEC.java:1211)
  • at com.webobjects.eoaccess.EODatabaseContext.objectsForSourceGlobalID(EODatabaseContext.java:4084)
  • at com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsForSourceGlobalID(EOObjectStoreCoordinator.java:

634)

  • at com.webobjects.eocontrol.EOEditingContext.objectsForSourceGlobalID(EOEditingContext.java:3923)
  • at er.extensions.eof.ERXEC.objectsForSourceGlobalID(ERXEC.java:1169)
  • at com.webobjects.eoaccess.EODatabaseContext._fireArrayFault(EODatabaseContext.java:4245)
  • at com.webobjects.eoaccess.EOAccessArrayFaultHandler.completeInitializationOfObject

(EOAccessArrayFaultHandler.java:77)

  • at com.webobjects.eocontrol._EOCheapCopyMutableArray.willRead(_EOCheapCopyMutableArray.java:37)
  • at com.webobjects.eocontrol._EOCheapCopyMutableArray.count(_EOCheapCopyMutableArray.java:86)
  • at com.mpv.evaluation.ClaimEvaluator.validateClaim(ClaimEvaluator.java:398)
  • ...

...Deadlock!

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BBC2, Top Gear - Series 15, Episode 1 - June 27 ’10

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#2 Actor Model

(A Share NOTHING Model)

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Slowmation

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Demo

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html5 <video>

<video poster="/slowmation/screenshots/0/2/4/425.jpg">

  • <source type="video/ogg" src="/slowmation/videos/6/d/8/423.ogg" />
  • <source type="video/mp4" src="/slowmation/videos/d/6/4/424.mp4" />

</video>

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HTML5 Video Conversion

Screenshot (.jpg) Video (.mp4)

Video (.ogg)

Thumbnail (.jpg)

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  • actor ! THUMBNAIL
  • actor ! GRAB
  • actor ! CONVERT2H264
  • actor ! CONVERT2OGG

Slowmation Actor

(Video Processor)

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!

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Actor Messaging

  • Asynchronous
  • Non-blocking
  • Immutable Messages
  • NO shared data
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Scala

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  • Immutable/Mutable datatypes
  • Anonymous Functions (~Closures)
  • No Static variables and methods
  • Extensible

Scala

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Scala

val greeting: String = “Hello World”;

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Scala

val greeting = “Hello World”;

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Scala

val greeting = “Hello World”

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Scala

val greeting = “Hello World” // immutable var response = new String() // mutable response = “Hey!”

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Java - Static Vars

public class _Talent extends EOGenericRecord { public static final String ENTITY_NAME = "Talent"; }

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Scala - Companion Object

  • bject Talent extends EOGenericRecord {

val ENTITY_NAME = "Talent" }

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Thread-Safe

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Scala - Pattern Matching

case a => { ... }

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Scala - Pattern Matching

try { var epi: EditPageInterface = D2W.factory.editPageForNewObjectWithEntityNamed(entityName, session) } catch { case e: IllegalArgumentException => { var epf: ErrorPageInterface = D2W.factory.errorPage(session) epf.setMessage(e.toString) } }

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Scala - Case Classes

case class PING case class PONG

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Scala - Case Classes

actor ! PING actor ! PONG

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Scala - Case Classes

case PING => { ... } case PONG => { ... }

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Scala - Anonymous Functions

x => x^2

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Scala - Anonymous Functions

x, y => x + y

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Scala - Anonymous Functions

x, y => {x + y}

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Scala - Anonymous Functions

case (PING => {...}) case (PONG => {...})

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λ - Expressions

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Scala Actors - Example

case class THUMBNAIL(filepath: String) // Actor msg case class val processor = actor { loop { react() { case THUMBNAIL(filepath: String) => { ... } } } } // asynchronous processor ! THUMBNAIL(“/Library/WebServer/Documents/slowmation/screenshots/0/2/4/422.jpg”)

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#2 Actor Model

  • EASY to program
  • Scalable
  • NO Deadlocks!
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Q: Why can Scala be used with WebObjects?

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A: Scala compiles to Java Byte-code

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WebObjects + Concurrency

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Why?

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Performance

  • Exploit multi-core processors
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Ajax

  • More responsive UI
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How?

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Properties

WOAllowsConcurrentRequestHandling=true

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Java - Synchronize Static Variables

private static String greeting = “Hello”; // private public void setGreeting(String aGreeting) { synchronized(greeting) { // synchronized block greeting = aGreeting; } }

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Free!

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WO - What is Shared?

  • Application
  • Session (concurrent WO)
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Use ERXEC

  • Project Wonder
  • Automatic lock/unlock handling
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Properties

er.extensions.ERXEC.safeLocking=true

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Debugging

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Demo

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Properties

  • Dcom.sun.management.jmxremote=true
  • Dcom.sun.management.jmxremote.authenticate=false
  • Dcom.sun.management.jmxremote.ssl=false

// Specific port

  • Dcom.sun.management.jmxremote.port=20102
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Bottlenecks

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  • Shared Object-cache
  • Antithesis to Share Nothing

model

  • Uses single database connection
  • Single-Threaded

EOF - Bottleneck

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#3 STM

(Software Transactional Memory)

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  • DOESN’T work in Scala Actors!
  • EOF + Scala
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  • Use Raw SQL
  • Alternative database access
  • Squeryl
  • ...

Solutions

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Squeryl

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Demo

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Squeryl

  • POSOs
  • Actor Compatible
  • Concurrent
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“Scala as a concurrent programming language is powerful, safe and easy-to-use”

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Benchmarks

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  • ERWOAdaptor (Mina)
  • WO Worker as Actor
  • Apache bench
  • c = 5...65
  • n = 500

The Test

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Results

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Time per req. (mean)

0 ms 50 ms 100 ms 150 ms 200 ms 5 10 15 20 25 30 35 40 45 50 55 60 65

WOAdaptor ERWOScalaAdaptor ERWOAdaptor

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Requests per second

200 400 600 800 5 10 15 20 25 30 35 40 45 50 55 60 65

WOAdaptor ERWOScalaAdaptor ERWOAdaptor

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“Scala as a concurrent programming language is powerful, safe and easy-to-use”

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In life long love The key Is R&D The ladder of invention Has eternal slide extension Rung by rung You’ll climb to heaven above. Constant innovation Guarantees a satiation Of that ever changing want And deepening need Nourishment and care To think anew… Makes passions flair And lets a culture breed Between the sheets…

  • by Emma Ahmad

The R&D Imperative

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Q&A

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  • What will

YOU do with 100 cores?

http://www.computerworld.com.au/article/354261/

  • WebObjects with Scala

http://wiki.objectstyle.org/confluence/display/WO/WebObjects+with+Scala

  • Case Study: Slowmation

http://slowmation.uow.edu.au

  • Source: ERWOScalaAdaptor

http://services.wocommunity.org/wowodc/ERWOScalaAdaptor

References