Shallow Dive:
Parallel Fx
Alex Moore
Software Developer, TDCI

No More Free Lunch
Processors not getting much faster

No More Free Lunch
transistors++

No More Free Lunch
transistors++ speed++

No More Free Lunch
transistors++ speed++

No More Free Lunch
transistors++ speed++
cores++

Elephant in the Room

Elephant in the Room
Parallel / Concurrent Programming is about
to reach it’s boiling point

Elephant in the Room
Can’t ignore it much longer

Elephant in the Room
There will be language, library, and tool
support for this soon.
There will be language, library, tool, and hardware support for this soon.
Concurrency is one of the main themes for C# 4.0, the PFX will probably be part of .Net 4.0,
Visual Studio 2010 will have tools to help better debug concurrent programs, and Intel’s next
Core processor, the i7, will have a whole slew of improvements to help run concurrent and
threaded applications better.

Parallel Extensions to
the .Net Framework
PLINQ
C
D Task Parallel Library
S
Scheduler
System.Threading

How to Express
Parallelism

How to Express
Parallelism
Threading sucks

How to Express
Parallelism
Declarative data parallelism - PLINQ

How to Express
Parallelism
Declarative data parallelism - PLINQ
Imperative data parallelism - Parallel.For

How to Express
Parallelism
Declarative data parallelism - PLINQ
Imperative data parallelism - Parallel.For
Imperative task parallelism - Tasks, Futures

PLINQ
from x in set
where x == somevalue
select expensiveFunction(x);

PLINQ
from x in set
where x == somevalue
select expensiveFunction(x);
from x in set.AsParallel()
where x == somevalue
select expensiveFunction(x);

Parallel.For
for( int i = 0; i < 10; i++ )
{ ... }

Parallel.For
for( int i = 0; i < 10; i++ )
{ ... }
Parallel.For( 0, 10, i =>
{ ... } );

Parallel.ForEach
foreach( var x in set ) { ... }

Parallel.ForEach
foreach( var x in set ) { ... }
Parallel.ForEach( set, x => {...});

Tasks
A();
B();
C();
Do_Something();

Tasks
Task t1 = Task.Create( ()=> A(); );
Task t2 = Task.Create( ()=> B(); );
Task t3 = Task.Create( ()=> C(); );
Task.WaitAll(t1, t2, t3);
Do_Something();

Futures
var a = A();
var b = B();
var c = C();
Do_Something(a,b,c);

Futures
var a = Future.Create( ()=> A(); );
var b = Future.Create( ()=> B(); );
var c = Future.Create( ()=> C(); );
Do_Something(a,b,c);

Demos

Box of Sharp Knives
PFX is a big box of sharp knives. Yes they are shiny and you want to grab them but be
careful.

Box of Sharp Knives
★ Not a silver bullet for performance
This should not be your first choice for improving performance. Clean “responsible” design
will go a long way when optimizing code, and will help when deciding where to apply
concurrency.

Box of Sharp Knives
★ Not a silver bullet for performance
✓ Get the CTP
✓ Read, Do, and Learn
This should not be your first choice for improving performance. Clean “responsible” design
will go a long way when optimizing code, and will help when deciding where to apply
concurrency.

Questions?
Comments ?
Are there any questions ? Comments ?

How to find info
• MSDN Magazine - October ‘08
• Channel 9 - “Parallel Extensions”
• Blogs: Joe Duffy, Herb Sutter
• http://geekswithblogs.net/alexmoore/
archive/2008/10/22/parallel-extensions-
links.aspx

Thanks!
Alex Moore
Blog: geekswithblogs.net/alexmoore
Twitter: @alexmoore