Multithreading
Multithreading
is used to perform multiple tasks at the same time. Tasks with the
potential of holding up other tasks can execute on separate threads, a
process known as multithreading. Or, it's basically trying to do more
than one thing at a time within a process.
Namespace
In
.NET, threading functionality is defined in the System.Threading
namespace. So you have to define System.Threading namespace before using
any thread classes.
using System.Threading;
Starting a Thread
A C#
client program starts in a single thread created automatically by the
CLR and operating system that is called the main thread, and is made
multithreaded by creating additional threads. Here's a simple example
and its output.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace multi
{
class Program
{
static void Main(string[] args)
{
Thread th = new Thread(WriteY);
th.Start();
for (int i = 0; i <= 10; i++)
{
Console.WriteLine("Hello");
}
}
private static void WriteY()
{
for (int i = 0; i <= 9; i++)
{
Console.Write("world");
}
}
}
}
OUTPUT
In the
above example, the main thread creates a new thread on which it runs a
method that repeatedly prints the string "world". Simultaneously, the
main thread repeatedly prints the string "Hello".
Abort a Thread
The Thread class's Abort method is called to abort a thread. Make sure you check the IsAlive property before Abort.
if (Thread.IsAlive)
{
{
Thread.Abort();
}
Here's a simple example and its output.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace multi
{
class Program
{
static void Main(string[] args)
{
Thread th = new Thread(WriteY);
if (th.IsAlive)
{
th.Start();
th.Abort();
}
for (int i = 0; i <= 10; i++)
{
Console.WriteLine("Hello");
}
}
private static void WriteY()
{
for (int i = 0; i <= 9; i++)
{
Console.WriteLine("world");
}
}
}
}
OUTPUT
In
the above example, The main thread creates a new thread which is
stopped by the abort method. The main thread repeatedly prints the
string "Hello".
Pausing a Thread
The Thread.Sleep method can be used to pause a thread for a fixed period of time.
Thread.Sleep()
Here's a simple example and its output.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace multi
{
class Program
{
static void Main(string[] args)
{
Thread th = new Thread(WriteY);
th.Start();
for (int i = 0; i <= 10; i++)
{
Console.WriteLine("Hello");
Thread.Sleep(1000);
}
}
private static void WriteY()
{
for (int i = 0; i <= 9; i++)
{
Console.WriteLine("world");
Thread.Sleep(500);
}
}
}
}
OUTPUT
In the above example, the main thread creates a new thread which is paused by the Sleep method for 500 milliseconds. The main thread is also paused by a Sleep method for 1000 milliseconds.
Thread Priority
The Thread class's ThreadPriority property is used to set the thread's priority. The thread priority can have Normal, AboveNormal, BelowNormal, Highest, and Lowest values.
Here's a simple example without priority and its output.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace multi
{
class Program
{
static void Main(string[] args)
{
Thread th = new Thread(WriteY);
th.Start();
for (int i = 0; i <= 10; i++)
{
Console.WriteLine("Hello");
}
}
private static void WriteY()
{
for (int i = 0; i <= 9; i++)
{
Console.WriteLine("world");
}
}
}
}
OUTPUT
Using With Lowest Priority
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace multi
{
class Program
{
static void Main(string[] args)
{
Thread th = new Thread(WriteY);
th.Priority = ThreadPriority.Lowest;
th.Start();
for (int i = 0; i <= 10; i++)
{
Console.WriteLine("Hello");
}
}
private static void WriteY()
{
for (int i = 0; i <= 9; i++)
{
Console.WriteLine("world");
}
}
}
}
OUTPUT
In
the above example defines the priority, the without priority example
executes the method writeY() but in the second example we defined the
lowest priority it will execute main method first.
Suspend a Thread
The Suspend method of the Thread class suspends a thread. The thread is suspended until the Resume method is called.
if (thread.ThreadState == ThreadState.Running)
{
{
thread.Suspend();
}
Resume a suspended Thread
The Resume method is called to resume a suspended thread. If the thread is not suspended, the Resume method will have no effect.
if (thread.ThreadState == ThreadState.Suspended) {
thread.Resume();
} 
