![从于舒仆仆 亟亠从仍从仂 舒从于
Task.WaitAll(Task[]) // with optional timeout
Task.WaitAny(Task[])](https://image.slidesharecdn.com/18multithreadingandparallelism-120601023032-phpapp01/85/Multithreading-and-parallelism-26-320.jpg)
![Continuations
舒亟舒舒: 仗仍 亰舒于亠亠仆仆 舒从舒 于亳从仂仆舒亳
仆舒仗仆亳亶.
仆舒仗仆仂仄 舒从 亟仂仗仆亳亶 亠亰仍舒
仗仂仗亠亠亟仆仂亞仂.
Task<U> Task<T>.ContinueWith(antecedent => {...});
TaskFactory.ContinueWhenAll(Task[], tasks => {...});](https://image.slidesharecdn.com/18multithreadingandparallelism-120601023032-phpapp01/85/Multithreading-and-parallelism-32-320.jpg)
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Multithreading and parallelism
- 1. Multithreading and Parallelism
- 2. Use cases - 舒舒弍仂于舒仆 仆舒 multi-CPU 仄舒亳仆舒 - 亳从仂仆舒仆仆 于亳亟亠 - 弍仂弍从舒 弍仍仂 从仍从仂 亰舒仗亳于 - 亳仂于于舒仆仆 亰舒亳仄仂从 (hiding latency) - 弍亳仍亠仆仆, 亟仂从亳 亠从舒仄仂 仆舒 IO - 亟亞从 UI (responsiveness) - 束丕仆亠仆仆晛 弍仍仂从ﾑ亳 仂仗亠舒亶
- 3. Threads
- 4. Process 仂亠 于亳亰仆舒舒 virtual address space. 仂磪舒 亰仂仍, 仂从仍从亳 - 仗仂亠亳 仆亠 仄仂亢 仆舒仗礆 舒亟亠于舒亳 仗舒仄 仆亳 仗仂亠于. 舒亰仂仄 亰 亳仄, 仗仍仆亠 于亳从仂亳舒仆仆: - 仗仍仆舒 弍弍仍仂亠从舒 仄仂亢亠 于仂亟亳亳 亟仂 舒亟亠仆仂亞仂 仗仂仂 从仍从仂 仗仂亠于.
- 5. 仂亠 仆亠 于亳从仂仆 从仂亟, 舒 仍亳亠 仆舒亟舒 亠亳 从仂仆亠从 亟仍 于亳从仂仆舒仆仆 仗仂仂从于
- 6. 仂仂从亳 (threads) 于亳从仂仆ﾑ 从仂亟 仂仂从亳 于亳从仂仆ﾑ 于 仄亠亢舒 仗仂亠 舒ﾑ 亟仂仗 亟仂 于仂亞仂 舒亟亠仆仂亞仂 仗仂仂 仗仂亠. 仂亢亠仆 仗仂从 仄舒 于亶 亠从 舒 亰仆舒亠仆仆 亠亞于 CPU
- 7. Windows - 舒亞舒仂亰舒亟舒仆舒 弌 - 亳仆ﾑ亠 仗仍舒仆于舒仆仆 仆舒 仂仆仂于 仗仂亳亠于 - (preemptive scheduling, priority-based) - 仂从 于亳从仂仆 仆舒 弍亟-磻仂仄 CPU - CPU 亰舒于亢亟亳 于亳从仂仆 仂亶 仗仂从, 磻亳亶 仄舒 仆舒亶于亳亳亶 仗仂亳亠 ( 磻亳亶 亞仂仂于亳亶 亟仂 于亳从仂仆舒仆仆)
- 8. 仍舒仆于舒仆仆 (scheduling) - 仂从 于亳从仂仆 仗仂磪仂仄 舒仍仂亞仂 仗亠仂亟 舒 从于舒仆 - 亠仍亳亳仆舒 从于舒仆于 仄仂亢亠 弍亳 亰仆舒, 亰舒仍亠亢亳 于亟: - 仂仆亞舒 亳亠仄亳 (从仂仂从, 亟仂于亞) - 弌舒舒 仗仂亠 (舒从亳于仆亳亶, 仂仆仂于亳亶) - 仂 亰舒从仆亠仆仆 从于舒仆舒 弌 仗亠亠于, 亳 亞仂仂于亳亶 仗仂从 亰 舒从亳仄 亢亠 仗仂亳亠仂仄 - 亊从 仍从亳 亰磦仍 仗仂从 亰 于亳亳仄 仗仂亳亠仂仄, 仗仂仂仆亳亶 仗仂从 于亳仆 - 舒于 磻仂 亶仂亞仂 从于舒仆 仆亠 亰舒从仆亳于
- 9. 亠亠从仍ﾑ亠仆仆 从仂仆亠从 (context switching) 亳弍舒于亳 仆仂于亳亶 仗仂从 亟仍 于亳从仂仆舒仆仆, 弌 仗亠亠从仍ﾑ舒 从仂仆亠从. 弍亠亞舒 舒仆 亠亞于 CPU + IP 仗仂仗亠亠亟仆仂亞仂 仗仂仂从. 亟仆仂于仍ﾑﾑ 亠亞亳 CPU 仆仂于仂亞仂 仗仂仂从.
- 10. 仂从 亰于仍仆 CPU, 从仂仍亳: - 亠亠仂亟亳 于 舒仆 仂从于舒仆仆 舒仄仂亶仆仂 - 亳从, 仄亠亠亢舒, 仗舒仄 (!), 亳仆仂仆亰舒 - 亳仆 仗仂仂从仂仄 亰 于亳亳仄 仗仂亳亠仂仄 - 亊从亳亶 亰舒从仆亳于 仂 仂从于舒亳 (亟亳从, 仄亠亠亢舒,...) - 仂亞仂 仗仂亳亠 亰弍仍亳于 - 舒于亠亳于 从于舒仆 - 舒于亠亳于 仗仂从
- 11. 亳仆舒仄仆亠 仗亟于亳亠仆仆 仗仂亳亠 - 仍 亰舒从仆亠仆仆 于于仂亟/于亳于仂亟 - 仍 亰舒从仆亠仆仆 仂从于舒仆仆 - 亳 仗仂弍亟亢亠仆仆 GUI 仗仂仂从于 亠亠亰 仂仗亠舒 亰 于从仆舒仄亳 - 仂仂于亳亶 亟仂 于亳从仂仆舒仆仆 仗仂从 亟仂于亳亶 舒 仆亠 仄舒 舒仆 于亳从仂仆舒亳 丐舒从仂亢 仗亳 仂仄 仄仂亢亠 亰弍仍于舒亳 从于舒仆.
- 12. 亳弍 CPU 亟仍 仗仂仂从 - 亳弍亳舒 仗仂亠仂, 磻亳亶 仗仂仂ﾑ - 亊从仂 仆亠仄舒 于仍仆仂亞仂 仗仂亠仂舒 于亳仆亠仆仆 仆舒 亟亠舒仍仆仂仄 仗仂亠仂
- 13. Scheduling granularity Windows 仗仍舒仆 仗仂仂从亳, 仆亠 仗仂亠亳 舒仍亟仂从: 仂亠 仄舒 1 仗仂从 仂亠 仄舒 9 仗仂仂从于 仂亠 仂亳仄舒 90% 仗仂亠仂仆仂亞仂 舒 (亰舒 仄仂于亳 仂亟仆舒从仂于仂亞仂 仗仂亳亠 仗仂仂从于)
- 14. Threads in .NET - 弌于仂亠仆仆 仗仂仂从: - new Thread(Action) - 舒仗从: - Thread.Start() - 从于舒仆仆 亟仂从亳 仗仂从 亰舒于亠亳: - Thread.Join()
- 15. Thread pool - 仍 仗仂仂从于 于亳从仂仆 亰舒于亟舒仆仆 于亳从仂亳仂于ﾑ亳 于亢亠 于仂亠仆亳亶 仆舒弍 仗仂仂从于 - 仂亟舒仆仆 仆仂于仂亞仂 亰舒于亟舒仆仆: - ThreadPool.QueueUserWorkItem(delegate)
- 16. UI message loop - 亟亳仆 GUI 仗仂从 仂弍仂弍仍 仗仂于亟仂仄仍亠仆仆 亰 亠亞亳: - Clicks, repaints, mouse moves, key presses, - 仂亟 仂弍仂弍仍ﾑ 仗仂仍亟仂于仆仂 - 亢亠, 磻仂 仂亟仆舒 仗仂亟 亰舒亶仄舒 亟仂于亞亳亶 舒, 亠舒 弍亟 亠从舒亳 - 亢亠, 亟仂于亞仂亳于舒仍 仗仂亟 仆从仂仍亳 仆亠 仗仂于亳仆仆 于亳从仂仆于舒亳 于 UI 仗仂仂 - IO, 于舒亢从 仂弍亳仍亠仆仆
- 17. 仆仂于仍亠仆仆 从仂仆仂仍于 - 乂仂弍 亰仄仆亳亳 从仂仆仂仍, 从仂亟 仗仂于亳仆亠仆 于亳从仂仆于舒亳 于 UI 仗仂仂 - 仆 仗仂仂从亳 仄仂亢 仗仂亞舒仄仆仂 亟仂亟舒亳 仗仂于亟仂仄仍亠仆仆 于 亠亞 UI 仗仂仂从
- 18. Demo
- 19. Task Parallel Library (TPL) Since .NET 4.0 http://msdn.microsoft.com/en-us/library/dd460717.aspx MSDN Parallel Computing Dev Center
- 20. Task http://msdn.microsoft.com/en-us/library/system.threading.tasks.task.aspx 弍舒亞 亰仆舒亠仆仆, 磻亠 弍亟亠* 亟仂仗仆亠 于 仄舒亶弍仆仂仄. 仆舒亠仆仆 亠亰仍舒仂仄 - 弍亳仍亠仆仆 (CPU) - 于仂亟 (IO) Task .NET 亠舒仍亰舒 future and promise
- 21. 仆舒亠仆仆 弍亟亠* 亟仂仗仆亠 - 仂亢仍亳于仂 于亢亠 亟仂仗仆亠 - 丐舒从 亰舒于亠亳于 亟仂 亰于亠仆亠仆仆 亰舒 亠亰仍舒仂仄, - 丐舒从仂亢 舒从 仄亞 于亳从仂仆舒亳 于 仂仄 亢 仗仂仂 - 仂亢仍亳于仂 仆亠 弍亟亠, 弍仂 舒仆亠 仗仂仄亳仍从舒 - 弍仂 仂弍亳仍亠仆仆 弍亟亠 于亟仄仆亠仆仂
- 22. 弌于仂亠仆仆 亰舒仗从 Task Task.Factory.StartNew(Action); Task<TResult> Task.Factory.StartNew(Func<TResult>); 弍仂 Task constructor + Task.Start() method
- 23. 亳从仂仆舒仆仆 Task 仆亠 仗仂从. 舒 亰舒仄仂于于舒仆仆礆 舒从亳 于亳从仂仆ﾑ 仗仂仂从舒仄亳 亰 thread pool 舒仍亟仂从 1: 舒从 仄仂亢亠 仗仂舒亳 于亳从仂仆于舒亳 仆亠 仂亟舒亰 舒仍亟仂从 2: 亟仂于亞仂亳于舒仍亳亶 舒从 弍亟亠 亰舒亶仄舒亳 仗仂从 亰 thread pool (亠亶 仗仂从 仆亠 亰仄仂亢亠 仗舒ﾐ火委亳 仆舒亟 亠仂 亰舒亟舒)
- 24. 亳从仂仆舒仆仆 亟仂于亞仂亳于舒仍仂亞仂 Task`舒 亟亠 于仂亠仆仂 仂从亠仄亳亶 仗仂从 Task.Factory.StartNew(() => { }, TaskCreationOptions.LongRunning);
- 25. 舒于亠亠仆仆, 亠亰仍舒 - Task.Wait() // with optional timeout - Task.Result 仂从 亰舒弍仍仂从, 仗仂从亳 舒从 仆亠 亰舒于亠亳
- 26. 从于舒仆仆 亟亠从仍从仂 舒从于 Task.WaitAll(Task[]) // with optional timeout Task.WaitAny(Task[])
- 27. Demo
- 28. Handle exceptions option 1 Task<int> t = Task.Factory.StartNew(() => { ... throw new InvalidOperationException("error"); return 42; }); 丐 于亳仆亳从仆亠 Exception int result = t.Result; AggregateException AggregateException.InnerException(s) 仄亳亳仄亠 仗仂舒从仂于亳亶 exception
- 29. Handle exceptions option 2 Check Task state: - Task.IsCompleted - Task.IsFaulted - Task.Exception AggregateException - Task.Status
- 30. Unhandled exceptions 亊从仂 仆亠 仂弍仂弍亳亳 exception, TPL 亶仂亞仂 仗亠亠于亳从亳仆亠 仗亳 仆舒仍亰舒 Taska 亳从仍亳亠 仗仂亟 TaskScheduler.UnobservedTaskException 仂仄亳仍从舒 于于舒亢舒 仂弍仂弍仍亠仆仂 仗亳: - 亳从仍亳从 Task.Result, Task.Wait() etc. - 于亠舒仆仆 亟仂 Task.Exception
- 31. Demo
- 32. Continuations 舒亟舒舒: 仗仍 亰舒于亠亠仆仆 舒从舒 于亳从仂仆舒亳 仆舒仗仆亳亶. 仆舒仗仆仂仄 舒从 亟仂仗仆亳亶 亠亰仍舒 仗仂仗亠亠亟仆仂亞仂. Task<U> Task<T>.ContinueWith(antecedent => {...}); TaskFactory.ContinueWhenAll(Task[], tasks => {...});
- 33. Continuations, 仗仂仂弍亳 - One-to-one - Many-to-one - One-to-many - Chain
- 34. Demo
- 35. 亠磻 仗亳从仍舒亟亳 于亳从仂亳舒仆仆 Tasks - 仂磪仆亠仆仆 仗舒舒仍亠仍亰仄 - 亳从仂仆舒仆仆 CPU-bound 亰舒亟舒 仗舒舒仍亠仍仆仂 - 亳从仂仆舒仆仆 IO-bound 亰舒亟舒 仗舒舒仍亠仍仆仂 - Responsive UI Demo
- 36. 弌亳仆仂仆亰舒
- 37. Data race int count = 0; for (int i = 0; i < data.Length; i++) { var task = Task.Factory.StartNew(() => { count++; Not atomic! }); tasks.Add(task); } Task.WaitAll(tasks.ToArray());
- 38. Preemption Thread A reg = read count (1) Thread B reg = read count (1) inc reg (2) write reg to count (2) inc reg (2) write reg to count (2)
- 39. 亠仆仆 1 interlocked int count = 0; for (int i = 0; i < data.Length; i++) { var task = Task.Factory.StartNew(() => { Atomic, Interlocked.Increment(ref count); Flushes caches }); tasks.Add(task); } Task.WaitAll(tasks.ToArray());
- 40. 亠仆仆 2 locking (critical section) int count = 0; object syncRoot = new object(); for (int i = 0; i < data.Length; i++) { var task = Task.Factory.StartNew(() => { lock (syncRoot) Other threads { cannot acquire held lock count++; } }); tasks.Add(task); } Task.WaitAll(tasks.ToArray());
- 42. Parallel.For() and ForEach() 舒弍仍仂从, 亟仂从亳 于 亠舒 仆亠 于亳从仂仆舒ﾑ Parallel.For(0, data.Length, i => { 仄仂亢仍亳于 亰仂弍亳亳 Break, 仗亠亠亟舒于亳 state ProcessItem(data, i); }); Parallel.ForEach(data, value => { ProcessItem(value); });
- 43. Parallel LINQ (PLINQ) var result = from value in data.AsParallel() where value % 2 == 0 let cube = Math.Pow(value, 3) let processed = ProcessItem(value) select new { Cube = cube, Result = processed }; parallelResult.ToArray(); 亳从仂仆舒仆仆 仗仂仆亠
- 44. 舒仂 舒从仂亢 亟亰仆舒亳 仗仂: - Task.Status, Task lifecycle http://blogs.msdn.com/b/pfxteam/archive/2009/08/30/9889070.aspx - Continuations http://msdn.microsoft.com/en-us/library/dd235663 - TaskSchedulers http://msdn.microsoft.com/en-us/library/dd997402 - Cancellation http://msdn.microsoft.com/en-us/library/dd997364.aspx - Synchronization primitives http://msdn.microsoft.com/en- us/library/ms228964.aspx - Concurrent collections http://msdn.microsoft.com/en- us/library/system.collections.concurrent.aspx - 亠亰仗仍舒仆舒 从仆亳亢从舒, 亠 仂亟仆舒