Streams in .NET. Part 1

This topic gives an introduction to using threads on the .NET platform. This is my first post on Habré, so do not judge very harshly. I would also like to hear constructive criticism on how to improve the material.

A thread is an independent sequence of instructions in a program. The easiest way to create threads is to call the delegate asynchronously.

static int TestThread( int data, int ms)
{
Console .WriteLine( "TestThread started" );
Thread.Sleep(ms);
Console .WriteLine( "TestThread completed" );
return ++data;
}

public delegate int TestThreadDelegate( int data, int ms);

* This source code was highlighted with Source Code Highlighter .

There are several ways to find out if a delegate has completed its work. This can be done using the BeginInvoke () method, in which the input parameters can be passed along with the delegate type. This method returns the type IAsyncResult, which has an IsCompleted property. The second way to wait for a result is to use a wait handle. You can access it using the AsyncWaitHandle property. The third way is to use asynchronous callback:

static void Main()
{

TestThreadDelegate d1 = TestThread;

d1.BeginInvoke(1, 3000, TestThreadCompleted, d1);
for ( int i = 0; i < 100; i++)
{
Console .Write( "." );
Thread.Sleep(50);
}

}

static void TestThreadCompleted(IAsyncResult ar)
{
if (ar == null ) throw new ArgumentNullException( "ar" );
TestThreadDelegate d1 = ar.AsyncState as TestThreadDelegate;
Trace.Assert(d1 != null , "Invalid object type" );

int result = d1.EndInvoke(ar);
Console .WriteLine( "result: {0}" , result);
}

* This source code was highlighted with Source Code Highlighter .

Another way to create threads is to use the Thread class. It also allows you to manage them.

using System;
using System.Threading;

namespace Csharp.Threading.FirstThread
{
class Program
{
static void Main( string [] args)
{
Thread t1 = new Thread(ThreadMain);
t1.Start();
Console .WriteLine( "This is the main thread." );
}
static void ThreadMain()
{
Console .WriteLine( "In thread." );
}
}
}

* This source code was highlighted with Source Code Highlighter .

You can transfer data to threads in two ways: using the Thread constructor with the ParameterizedThreadStart delegate, or by creating a special class and defining the thread method as an instance method:

public class MyThread
{
private string data;

public MyThread( string data)
{
this .data = data;
}

public void ThreadMain()
{
Console .WriteLine( "Running in a thread, data: {0}" , data);
}
}

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In Main:

MyThread obj = new myThread(“text”);

Thread tr = new Thread(obj.ThreadMain);

tr.Start();

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There are two types of threads: priority and background. The process continues until at least one priority thread is executed. With the help of the Thread class, it is created by default. To make the stream background, use the IsBackground property.

The operating system schedules the execution order of the threads. This process can be influenced by assigning the appropriate priority to the thread using the Priority property.

Sometimes it is necessary to create a set of threads in advance, also to increase or decrease this set when necessary. For this, the ThreadPool class is provided.

using System;
using System.Threading;

namespace Csharp.Threading.Pools
{

class Program
{
static void Main()
{

for ( int i = 0; i < 5; i++)
{
ThreadPool.QueueUserWorkItem(JobForAThread);

}

Thread.Sleep(5000);
}

static void JobForAThread( object state)
{
for ( int i = 0; i < 3; i++)
{
Console .WriteLine( "loop {0}, running inside pooled thread {1}" , i,
Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(10);
}

}
}
}

* This source code was highlighted with Source Code Highlighter .

But thread pools have some limitations: they are background, you can not change the priority or the name of the thread in the pool either.
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For starters, that's all. Next time we'll talk about deadlock and thread synchronization.

UPD. Transferred to .NET. Thanks for the karma.