Multithreading with C# Cookbook, Second Edition

Multithreading with C# Cookbook, Second Edition - Second Edition

By : Evgenii Agafonov

Buy this Book

Multithreading with C# Cookbook, Second Edition - Second Edition

By: Evgenii Agafonov

Buy this Book

Overview of this book

Multi-core processors are synonymous with computing speed and power in today’s world, which is why multithreading has become a key concern for C# developers. Multithreaded code helps you create effective, scalable, and responsive applications. This is an easy-to-follow guide that will show you difficult programming problems in context. You will learn how to solve them with practical, hands-on, recipes. With these recipes, you’ll be able to start creating your own scalable and reliable multithreaded applications. Starting from learning what a thread is, we guide you through the basics and then move on to more advanced concepts such as task parallel libraries, C# asynchronous functions, and much more. Rewritten to the latest C# specification, C# 6, and updated with new and modern recipes to help you make the most of the hardware you have available, this book will help you push the boundaries of what you thought possible in C#.

Multithreading with C# Cookbook Second Edition

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

A 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 the Task Parallel Library

Introduction

Creating a task

Performing basic operations with a task

Combining tasks

Converting the APM pattern to tasks

Converting the EAP pattern to tasks

Implementing a cancelation option

Handling exceptions in tasks

Running tasks in parallel

Tweaking the execution of tasks with TaskScheduler

Using C# 6.0

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

Handling exceptions in asynchronous operations

Avoiding the use of 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 with 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 an asynchronous Observable

Writing custom Observable

Using the Subject type family

Creating an Observable object

Using LINQ queries against an 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 Universal Windows Platform application

Using WinRT from usual applications

Using BackgroundTask in Universal Windows Platform applications

Running a .NET Core application on OS X

Running a .NET Core application on Ubuntu Linux

Index

Customer Reviews

5 star

4 star

3 star

2 star

1 star

Determining a thread state

This recipe will describe the 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. 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 2015. 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 2015. Create a new C# console application project.

In the Program.cs file, add the following using directives:

using System;
using System.Threading;
using static System.Console;
using static System.Threading.Thread;

Add the following code snippet below the Main method:

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

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

Add the following code snippet inside the Main method:

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

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

If this 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. 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 was completed successfully and now has a ThreadState.Stopped state. There are several other states, but they are partly deprecated and not as useful as those we examined.

Multithreading with C# Cookbook, Second Edition - Second Edition

By : Evgenii Agafonov

Multithreading with C# Cookbook, Second Edition - Second Edition

By: Evgenii Agafonov

Overview of this book

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Current Title:

Multithreading with C# Cookbook, Second Edition - Second Edition

Determining a thread state

Getting ready

How to do it...

How it works...

Tip