1. H IGH - LEVEL M ULTITHREADED P ROGRAMMING [P ART II] Primož Gabrijelčič

2. B ACKGROUND I NFORMATION

3. About Me Primož Gabrijelčič Programmer, consultant, writer, speaker – thedelphigeek.com – www.glagolite.si/delphi Hacking multithreaded code since 1999

4. About OmniThreadLibrary „VCL for multithreading“ Delphi 2007 – XE3[4] Open source – OpenBSD license – www.omnithreadlibrary.com – omnithreadlibrary.googlecode.com Win32/Win64

5. About the Webinars Code and video: www.omnithreadlibrary.com/webinars Code = free, video = $10 20 free books, courtesy of the De Novo Software, www.denovosoftware.com

6. High-Level Abstractions Async [/Await] Future Join ForEach ParallelTask BackgroundWorker ForkJoin Pipeline

7. High-Level Abstractions Async [/Await] Future Join ForEach ParallelTask BackgroundWorker ForkJoin Pipeline Start multiple background tasks [and wait]

8. Join

9. High-Level Abstractions Async [/Await] Future Join ForEach ParallelTask BackgroundWorker ForkJoin Pipeline Start multiple copies of a single task

10. ParallelTask

11. High-Level Abstractions Async [/Await] Future Join ForEach ParallelTask BackgroundWorker ForkJoin Pipeline Background request-processing service

12. Background Worker

13. BackgroundWorker Usage service := Paralell.BackgroundWorker. OnRequestDone(code1).Execute(code2); workItem := service.CreateWorkItem(data); service.Schedule(workItem) service.Terminate; service := nil;

14. High-Level Abstractions Async [/Await] Future Join ForEach ParallelTask BackgroundWorker ForkJoin Pipeline Divide and conquer

15. Fork/Join

16. Fork/Join Usage computation := Parallel.ForkJoin; compute1 := computation.Compute(action); – Inside action: computation.Compute(newAction) compute2 := computation.Compute(action); compute1.Value / compute1.Await compute2.Value / compute2.Await

17. P ARTING N OTES

18. Keep in Mind Don’t parallelize everything Rethink the algorithm Data flow dictates the abstraction Measure the improvements Test, test and test

19. Code & Video Will be available shortly at www.omnithreadlibrary.com/webinars