[Solved] How to create and use background thread to change object from another thread

by


A background thread is scoped to the main thread. So it’ll run as long as the console app is alive. .Net has a rich threading library, so I leave it up to you.

for ex)
1) use a delegate and call BeginInvoke
2) system.threading.Thread namespace
3) System.Threading.Tasks namespace

Since threading can be daunting, here’s a sample console app that should do almost what you need.

run the app and once your comfy with the basics, you can write your own.

using System;
using System.Collections.Generic;
using System.Threading;

/// <summary>
/// Represent a hard working employee.
/// 
/// The employee will process a job, once it comes in.
/// 
/// 
/// </summary>
public class Employee
{
    private Queue<string> _tasksTray;
    private string _employeeID;

    public Employee(string employeeID, Queue<string> taskTray)
    {
        //employee's ID number.  
        this._employeeID = employeeID;

        //get a reference to the task tray
        this._tasksTray = taskTray;

        //fire up a worker thread
        var thread = new Thread(new ThreadStart(this.Run));
        thread.IsBackground = true;
        thread.Start();
    }

    private void Run()
    {
        string myTask = null;

        //time to work until i die
        while (true)
        {
            //discard the old task, if any
            myTask = string.Empty;

            //check if we have anything to do
            if (this._tasksTray.Count == 0)
            {
                lock (this._tasksTray)
                {
                    //no jobs; time to chill.
                    Console.WriteLine("Employee# {0} is taking a break.", this._employeeID);
                    Monitor.Wait(this._tasksTray);
                }
            }

            //work finally came in. Grab the tray and get a task.
            lock (this._tasksTray)
            {
                if (this._tasksTray.Count > 0)
                {
                    //yes, i got a job. Remove the task from the tray, so no one else can get it.
                    myTask = this._tasksTray.Dequeue();
                }
            }

            //time to process the task
            if (!string.IsNullOrEmpty(myTask))
            {
                Console.WriteLine("Employee# {0} has completed job: {1}.", this._employeeID, myTask);
                Thread.Sleep(1000);
            }
        }
    }
}

/// <summary>
/// Represent your standard manager that manages a tray of jobs.
///  
/// for ex)
/// 1) he has a certain number of employees.
/// 2) he interacts with clients and get jobs
/// 3) he post jobs to JIRA and notifies his employees to start working.
/// </summary>
public class Manager
{
    private Queue<string> _taskTray;
    private List<Employee> _employees;

    public Manager(int numOfEmployees = 5)
    {
        //Tray of jobs. This is a shared resource between the manager and employees, so we have to make sure only one person access it at any time.
        this._taskTray = new Queue<string>();

        //set employees
        this._employees = new List<Employee>();
        for (var i = 0; i < numOfEmployees; i++)
        {
            this._employees.Add(new Employee(i.ToString(), this._taskTray));
        }
    }

    public void AddTask(params string[] newTasks)
    {
        lock (this._taskTray)
        {
            //add new tasks to the tray
            foreach (var task in newTasks)
            {
                this._taskTray.Enqueue(task);
            }


            //break time over. time to get back to work.
            Console.WriteLine("\nManager said: Wake up. Time to work. We got {0} jobs.\n", newTasks.Length);
            Monitor.PulseAll(this._taskTray);
        }
    }

}


//Main
class Program
{

    static void Main(string[] args)
    {
        try
        {
            //create a manager
            var manager = new Manager(3);

            //add jobs
            manager.AddTask("Task 1", "task 2");

            //simulate downtime
            Thread.Sleep(5000);

            //add more jobs
            var jobs = new List<string>();
            for (int i = 0; i < 10; i++)
            {
                jobs.Add("Project# " + i.ToString());
            }
            manager.AddTask(jobs.ToArray());

        }
        catch (Exception ex)
        {

            Console.WriteLine(ex.Message);
        }

        Console.WriteLine("press any key to end the program.");
        Console.Read();
    }


}

solved How to create and use background thread to change object from another thread