Fire and forget method in C#

Question

Fire and forget method in C#

I refered different issues for 'Fire and Forget in C#'

i.e. Simplest way to do a fire and forget method in C#? . . and few several,

but i have an another issue with the same.i wrote following code

static void Main(string[] args)
    {
        for (int i = 0; i < 5; i++)
        {
            //fireAway(i);
            Task.Factory.StartNew(() => fireAway(i));
        }
        Console.WriteLine("Main Finished");
        Console.Read();
    }

public static void fireAway(int i)
    {
        System.Threading.Thread.Sleep(5000);
        Console.WriteLine("FireAway" + i);
    }

where i am expecting output like

Main Finished

FireAway0

FireAway1

FireAway2

FireAway3

FireAway4

but output is

Main Finished

FireAway5

very honestly i am new to threading concept, i need help. How can i meet with expected output..?

http://stackoverflow.com/questions/271440/captured-variable-in-a-loop-in-c-sharp — Dmitry Bychenko, Mar 22 '16 at 12:36
fireaway method closes over (i) variable, and since you're waiting in that method for 5 seconds, (i) will become 5 before you write it's value — Nikola.Lukovic, Mar 22 '16 at 12:38

score 1 · Answer 1 · edited Mar 22 '16 at 12:50

1

The threads are started after the loop is finished. When the loop is finished the value of i is 5. You have to capture the value of i before you send it to StartNew(..)

for (int i = 0; i < 5; i++)
{
      int tmp = i;
      Task.Factory.StartNew(() => fireAway(tmp));
}

edited Mar 22 '16 at 12:50

Vadim Martynov

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answered Mar 22 '16 at 12:39

mortb

9,361
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score -1 · Answer 2 · answered Mar 22 '16 at 12:37

-1

You should pass parameter to your method, not use i, because the method will start to execute only after you finish to iterate, see here

answered Mar 22 '16 at 12:37

Buda Gavril

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Fire and forget method in C#

2 Answers2