Multithreading in C# 5.0 Cookbook

Multithreading in C# 5.0 Cookbook

By : Evgenii Agafonov

Buy this Book

Multithreading in C# 5.0 Cookbook

By: Evgenii Agafonov

Buy this Book

Overview of this book

In an age when computer processors are being developed to contain more and more cores, multithreading is a key factor for creating scalable, effective, and responsive applications. If you fail to do it correctly, it can lead to puzzling problems that take a huge amount of time to resolve. Therefore, having a solid understanding of multithreading is a must for the modern application developer. Multithreading in C# 5.0 Cookbook is an easy-to-understand guide to the most puzzling programming problems. This book will guide you through practical examples dedicated to various aspects of multithreading in C# on Windows and will give you a good basis of practical knowledge which you can then use to program your own scalable and reliable multithreaded applications. This book guides you through asynchronous and parallel programming from basic examples to practical, real-world solutions to complex problems. You will start from the very beginning, learning what a thread is, and then proceed to learn new concepts based on the information you get from the previous examples. After describing the basics of threading, you will be able to grasp more advanced concepts like Task Parallel Library and C# asynchronous functions. Then, we move towards parallel programming, starting with basic data structures and gradually progressing to the more advanced patterns. The book concludes with a discussion of the specifics of Windows 8 application programming, giving you a complete understanding of how Windows 8 applications are different and how to program asynchronous applications for Windows 8.

Multithreading in C# 5.0 Cookbook

Credits

About the Author

About the Reviewers

www.PacktPub.com

Preface

Free Chapter

Threading Basics

Introduction

Creating a thread in C#

Pausing a thread

Making a thread wait

Aborting a thread

Determining a thread state

Thread priority

Foreground and background threads

Passing parameters to a thread

Locking with a C# lock keyword

Locking with a Monitor construct

Handling exceptions

Thread Synchronization

Introduction

Performing basic atomic operations

Using the Mutex construct

Using the SemaphoreSlim construct

Using the AutoResetEvent construct

Using the ManualResetEventSlim construct

Using the CountDownEvent construct

Using the Barrier construct

Using the ReaderWriterLockSlim construct

Using the SpinWait construct

Using a Thread Pool

Introduction

Invoking a delegate on a thread pool

Posting an asynchronous operation on a thread pool

Thread pool and the degree of parallelism

Implementing a cancellation option

Using a wait handle and timeout with a thread pool

Using a timer

Using the BackgroundWorker component

Using Task Parallel Library

Introduction

Creating a task

Performing basic operations with a task

Combining tasks together

Converting the APM pattern to tasks

Converting the EAP pattern to tasks

Implementing a cancellation option

Handling exceptions in tasks

Running tasks in parallel

Tweaking tasks execution with TaskScheduler

Using C# 5.0

Introduction

Using the await operator to get asynchronous task results

Using the await operator in a lambda expression

Using the await operator with consequent asynchronous tasks

Using the await operator for the execution of parallel asynchronous tasks execution

Handling exceptions in the asynchronous operations

Avoid using the captured synchronization context

Working around the async void method

Designing a custom awaitable type

Using the dynamic type with await

Using Concurrent Collections

Introduction

Using ConcurrentDictionary

Implementing asynchronous processing using ConcurrentQueue

Changing asynchronous processing order ConcurrentStack

Creating a scalable crawler with ConcurrentBag

Generalizing asynchronous processing with BlockingCollection

Using PLINQ

Introduction

Using the Parallel class

Parallelizing a LINQ query

Tweaking the parameters of a PLINQ query

Handling exceptions in a PLINQ query

Managing data partitioning in a PLINQ query

Creating a custom aggregator for a PLINQ query

Reactive Extensions

Introduction

Converting a collection to asynchronous Observable

Writing custom Observable

Using Subjects

Creating an Observable object

Using LINQ queries against the observable collection

Creating asynchronous operations with Rx

Using Asynchronous I/O

Introduction

Working with files asynchronously

Writing an asynchronous HTTP server and client

Working with a database asynchronously

Calling a WCF service asynchronously

Parallel Programming Patterns

Introduction

Implementing Lazy-evaluated shared states

Implementing Parallel Pipeline with BlockingCollection

Implementing Parallel Pipeline with TPL DataFlow

Implementing Map/Reduce with PLINQ

There's More

Introduction

Using a timer in a Windows Store application

Using WinRT from usual applications

Using BackgroundTask in Windows Store applications

Index

Customer Reviews

5 star

4 star

3 star

2 star

1 star

Determining a thread state

This recipe will describe possible states a thread could have. It is useful to get information about whether a thread is started yet or whether it is in a blocked state. Please note that because a thread runs independently, its state could be changed at any time.

Getting ready

To work through this recipe, you will need Visual Studio 2012. There are no other prerequisites. The source code for this recipe can be found at BookSamples\Chapter1\Recipe5.

How to do it...

To understand how to determine a thread state and acquire useful information about it, perform the following steps:

Start Visual Studio 2012. Create a new C# Console Application project.
In the Program.cs file, add the following using directives:
```
using System;
using System.Threading;
```

Add the following code snippet below the Main method:

static void DoNothing()
{
  Thread.Sleep(TimeSpan.FromSeconds(2));
}

static void PrintNumbersWithStatus()
{
  Console.WriteLine("Starting...");
  Console.WriteLine(Thread.CurrentThread
  .ThreadState.ToString());
  for (int i = 1; i < 10; i++)
  {
    Thread.Sleep(TimeSpan.FromSeconds(2));
    Console.WriteLine(i);
  }
}

Add the following code snippet inside the Main method:

Console.WriteLine("Starting program...");
Thread t = new Thread(PrintNumbersWithStatus);
Thread t2 = new Thread(DoNothing);
Console.WriteLine(t.ThreadState.ToString());
t2.Start();
t.Start();
for (int i = 1; i < 30; i++)
{
  Console.WriteLine(t.ThreadState.ToString());
}
Thread.Sleep(TimeSpan.FromSeconds(6));
t.Abort();
Console.WriteLine("A thread has been aborted");
Console.WriteLine(t.ThreadState.ToString());
Console.WriteLine(t2.ThreadState.ToString());

Run the program.

How it works...

When the main program starts it defines two different threads; one of them will be aborted and the other runs successfully. The thread state is located in the ThreadState property of a Thread object, which is a C# enumeration. At first the thread has a ThreadState.Unstarted state. Then we run it and assume that, for the duration of 30 iterations of a cycle, the thread will change its state from ThreadState.Running to ThreadState.WaitSleepJoin.

Tip

Please note that the current Thread object is always accessible through the Thread.CurrentThread static property.

If it does not happen, just increase the number of iterations. Then we abort the first thread and see that now it has a ThreadState.Aborted state. It is also possible that the program will print out the ThreadState.AbortRequested state. This illustrates very well the complexity of synchronizing two threads. Please keep in mind that you should not use thread abortion in your programs. I've covered it here only to show the corresponding thread state.

Finally, we can see that our second thread t2 completed successfully and now has a ThreadState.Stopped state. There are several other states, but they are partly deprecated and partly not as useful as those we examined.

Multithreading in C# 5.0 Cookbook

By : Evgenii Agafonov

Multithreading in C# 5.0 Cookbook

By: Evgenii Agafonov

Overview of this book

Related Content you might be interested in

Current Title:

Multithreading in C# 5.0 Cookbook

Determining a thread state

Getting ready

How to do it...

How it works...

Tip