How to wait for the thread to end before continuing with the program

Question

I have this simple program using threads in C#. How can I make sure that all the threads are done executing before I do a Console.ReadKey(); to terminate the program (else it goes straight to the ReadKey and I have to press it for the threads to keep executing)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace Partie_3
{
    class Program
    {
        static int _intToManipulate;
        static object _lock;
        static Thread thread1;
        static Thread thread2;

        static void Main(string[] args)
        {
            _intToManipulate = 0;

            _lock = new object();

            thread1 = new Thread(increment);
            thread2 = new Thread(decrement);

            thread1.Start();
            thread2.Start();

            Console.WriteLine("Done");
            Console.ReadKey(true);
        }



        static void increment()
        {
            lock (_lock)
            {
                _intToManipulate++;
                Console.WriteLine("increment : " + _intToManipulate);
            }
        }
        static void decrement()
        {
            lock (_lock)
            {
                _intToManipulate--;
                Console.WriteLine("decrement : " + _intToManipulate);
            }
        }
    }
}

score 3 · Accepted Answer · answered Nov 04 '12 at 17:59

3

You're looking for Thread.Join():

thread1.Start();
thread2.Start();

thread1.Join();
thread2.Join();

Console.WriteLine("Done");
Console.ReadKey(true);

answered Nov 04 '12 at 17:59

Patrick Quirk

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3

That said, it's probably a lot wiser to be using the TPL instead of manually mucking about with `Thread` objects. – Daniel Mann Nov 04 '12 at 18:02

score 3 · Answer 2 · edited May 23 '17 at 12:04

A similar question can be found here: C#: Waiting for all threads to complete

With C# 4.0+ I personally prefer to use Tasks instead of Threads and wait for them to complete as mentioned in the second highest voted answer:

for (int i = 0; i < N; i++)
{
     tasks[i] = Task.Factory.StartNew(() =>
     {               
          DoThreadStuff(localData);
     });
}
while (tasks.Any(t => !t.IsCompleted)) { } //spin wait

Console.WriteLine("All my threads/tasks have completed. Ready to continue");

If you've got little experience with Threads and Tasks, I'd recommend going down the Tasks route. Comparitively, they're really simple to use.

How to wait for the thread to end before continuing with the program

2 Answers2

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