GPars Quick Hits

GPars Quick Hits Eric Sword

Who am I
Professional geek for 17 years
Former head of engineering here at Group Logic
Now full-time dev and tech lead for SAIC
Blog: http://www.swordsystems.com
[email_address]

All Together Now
JEEPERS!

Why GPars?
Concise
Avoids errors with thread management
No creating threads or managing pool
Easy to Start
Rolled into Groovy 1.8
import groovyx.gpars.XXX

Who?
Vaclav Pech started it in 2008
http://www.jroller.com/vaclav/
Jetbrains (makers of Intellij IDEA) employee?
Very responsive
Keeps an eye on GPars news

How?
Grab
Maven
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-all</artifactId>
<version>1.8.2</version>
</dependency>
<dependency>
<groupId>org.codehaus.gpars</groupId>
<artifactId>gpars</artifactId>
<version>0.12</version>
</dependency>
@Grab('org.codehaus.gpars:gpars:0.12')

Version Dependency Hassles
Groovy bundled with 0.11, but 0.12 is out
0.11 -> org.coconut.forkjoin:jsr166y-070108.jar
Or maybe jsr166y-070108.jar???
0.12 -> org.codehaus.jsr166-mirror
jsr166y-1.7.0.jar
extra166y-1.7.0.jar

4 Main Parts
Async Collections and Closures
Actors like Scala
Dataflow
Agents like Clojure

Collection Fork-Join
each,collect,find , etc become parallel
See Re-GINA 17.2.2 for full list
Insert wherever you want
No re-architecture

Collections - code import static groovyx.gpars.GParsPool.withPool def urls = [...some urls here...] withPool { urls.collectParallel{it.text} }
You will see withPool a lot

Collections – code withPool { urls.makeConcurrent().collect{it.text} } //chain together withPool { urls.makeConcurrent() .collect{it.text} .findAll{it.contains 'GROOVY'} .size()} }

Warning: Breaking API Changes
Big changes from 0.10 to 0.12
Calls deprecated in 0.11, removed in 0.12
makeTransparent -> makeConcurrent
Beware some examples in Ref Guide
Beware tutorials written for <=0.10
http://gpars.codehaus.org/Breaking+Changes

Collection cont...
Show me some code...

Exception Handling
If one call throws exception, whole closure will throw after all complete.
Example...

Map-Reduce
Like regular collections, but no choke point
map -> collect, filter -> findAll
From ReGina, Figure 17.1

Closures
AsyncFun

Testing
Test your code, not Gpars

Testing
Test your code, not Gpars
Bonus! Your code doesn't change

Using Gpars for Testing
http://www.slideshare.net/paulk_asert/groovy-and-concurrency - slide 102

Behind The Scenes
withPool uses a category to add the methods to collections, closures, etc.
Actual code in GparsPoolUtil
Map-Reduce methods also in that file in contained class PAWrapper

Resources
http://gpars.codehaus.org
http://git.codehaus.org/gitweb.cgi?p=gpars.git;a=tree;f=src/test/groovy/groovyx/gpars/samples
http://www.manning.com/koenig2/
http://www.slideshare.net/gr8conf/g-pars-vaclavpech2011
http://www.slideshare.net/VaclavPech/pick-up-the-lowhanging-concurrency-fruit
http://skillsmatter.com/podcast/groovy-grails/concurrent-programming-for-you-and-me
starts a little slow, but around minute 16, gives some good examples
http://groovy.codehaus.org/Guy+Steele%27s+word+split+example+using+Groovy+and+GPars
http://www.slideshare.net/paulk_asert/groovy-and-concurrency

Thanks!
Happy Parallelizing
http://www.swordsystems.com
http://www.slideshare.net/ericsword/gpars-quick-hits
[email_address]

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GPars Quick Hits

by ericsword on Sep 27, 2011

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GPars Quick Hits — Presentation Transcript