thread with multiple parameters

Question

Does anyone know how to pass multiple parameters into a Thread.Start routine?

I thought of extending the class, but the C# Thread class is sealed.

Here is what I think the code would look like:

...
    Thread standardTCPServerThread = new Thread(startSocketServerAsThread);

    standardServerThread.Start( orchestrator, initializeMemberBalance, arg, 60000);
...
}

static void startSocketServerAsThread(ServiceOrchestrator orchestrator, List<int> memberBalances, string arg, int port)
{
  startSocketServer(orchestrator, memberBalances, arg, port);
}

BTW, I start a number of threads with different orchestrators, balances and ports. Please consider thread safety also.

serhio · Accepted Answer · 2010-05-14 11:30:34Z

71

Try using a lambda expression to capture the arguments.

Thread standardTCPServerThread = 
  new Thread(
    unused => startSocketServerAsThread(initializeMemberBalance, arg, 60000)
  );

edited May 14, 2010 at 11:30

serhio

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answered May 6, 2009 at 18:32

JaredPar

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4 Comments

Joshua Belden Over a year ago

How safe is that to execute the expression on a seperate thread?

Reed Copsey Over a year ago

This is safe - with caveats. It can have some strange side-effects, though, if you tweak your variables immediately after calling this, since you're effectively passing the variables in by reference.

tmaj Over a year ago

Beacuse of what @Reed Copsey explained don't do :for(int i = 0; i < howMany; i++) { Thread t = new Thread(unused => startSocketServerAsThread( x, y, i) ); t.Start(); }. Use a 'proxy' like int toPass = i;

Eboubaker Over a year ago

does this capture references as well?

Hamed · Accepted Answer · 2012-06-02 13:43:25Z

20

Here is a bit of code that uses the object array approach mentioned here a couple times.

    ...
    string p1 = "Yada yada.";
    long p2 = 4715821396025;
    int p3 = 4096;
    object args = new object[3] { p1, p2, p3 };
    Thread b1 = new Thread(new ParameterizedThreadStart(worker));
    b1.Start(args);
    ...
    private void worker(object args)
    {
      Array argArray = new object[3];
      argArray = (Array)args;
      string p1 = (string)argArray.GetValue(0);
      long p2 = (long)argArray.GetValue(1);
      int p3 = (int)argArray.GetValue(2);
      ...
    }>

edited Jun 2, 2012 at 13:43

Hamed

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answered Apr 10, 2010 at 4:01

Opus

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1 Comment

Lucas B Over a year ago

@Opus I think the lambda expression, JaredPar's solution, is easier to maintain (read, understand, and update)

Reed Copsey · Accepted Answer · 2009-05-06 18:31:35Z

12

You need to wrap them into a single object.

Making a custom class to pass in your parameters is one option. You can also use an array or list of objects, and set all of your parameters in that.

answered May 6, 2009 at 18:31

Reed Copsey

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Comments

Frederik Gheysels · Accepted Answer · 2009-05-06 18:35:42Z

7

Use the 'Task' pattern:

public class MyTask
{
   string _a;
   int _b;
   int _c;
   float _d;

   public event EventHandler Finished;

   public MyTask( string a, int b, int c, float d )
   {
      _a = a;
      _b = b;
      _c = c;
      _d = d;
   }

   public void DoWork()
   {
       Thread t = new Thread(new ThreadStart(DoWorkCore));
       t.Start();
   }

   private void DoWorkCore()
   {
      // do some stuff
      OnFinished();
   }

   protected virtual void OnFinished()
   {
      // raise finished in a threadsafe way 
   }
}

answered May 6, 2009 at 18:35

Frederik Gheysels

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Comments

Brian Gideon · Accepted Answer · 2010-11-18 15:55:19Z

6

.NET 2 conversion of JaredPar answer

Thread standardTCPServerThread = new Thread(delegate (object unused) {
        startSocketServerAsThread(initializeMemberBalance, arg, 60000);
    });

edited Nov 18, 2010 at 15:55

Brian Gideon

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answered Nov 18, 2010 at 15:50

Aaron P. Olds

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Comments

Muhammad Mubashir · Accepted Answer · 2012-12-24 11:57:08Z

6

void RunFromHere()
{
    string param1 = "hello";
    int param2 = 42;

    Thread thread = new Thread(delegate()
    {
        MyParametrizedMethod(param1,param2);
    });
    thread.Start();
}

void MyParametrizedMethod(string p,int i)
{
// some code.
}

answered Dec 24, 2012 at 11:57

Muhammad Mubashir

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Comments

Kamarey · Accepted Answer · 2009-05-06 18:31:48Z

3

You can't. Create an object that contain params you need, and pass is it. In the thread function cast the object back to its type.

answered May 6, 2009 at 18:31

Kamarey

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Comments

Andro Selva · Accepted Answer · 2012-11-15 07:00:43Z

I've been reading yours forum to find out how to do it and I did it in that way - might be useful for somebody. I pass arguments in constructor which creates for me working thread in which will be executed my method - execute() method.

 using System;

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Windows.Forms;
using System.IO;
using System.Threading;
namespace Haart_Trainer_App

{
    class ProcessRunner
    {
        private string process = "";
        private string args = "";
        private ListBox output = null;
        private Thread t = null;

    public ProcessRunner(string process, string args, ref ListBox output)
    {
        this.process = process;
        this.args = args;
        this.output = output;
        t = new Thread(new ThreadStart(this.execute));
        t.Start();

    }
    private void execute()
    {
        Process proc = new Process();
        proc.StartInfo.FileName = process;
        proc.StartInfo.Arguments = args;
        proc.StartInfo.UseShellExecute = false;
        proc.StartInfo.RedirectStandardOutput = true;
        proc.Start();
        string outmsg;
        try
        {
            StreamReader read = proc.StandardOutput;

        while ((outmsg = read.ReadLine()) != null)
        {

                lock (output)
                {
                    output.Items.Add(outmsg);
                }

        }
        }
        catch (Exception e) 
        {
            lock (output)
            {
                output.Items.Add(e.Message);
            }
        }
        proc.WaitForExit();
        var exitCode = proc.ExitCode;
        proc.Close();

    }
}
}

Ali · Accepted Answer · 2017-07-28 13:31:02Z

1

You can take Object array and pass it in the thread. Pass

System.Threading.ParameterizedThreadStart(yourFunctionAddressWhichContailMultipleParameters)

Into thread constructor.

yourFunctionAddressWhichContailMultipleParameters(object[])

You already set all the value in objArray.

you need to abcThread.Start(objectArray)

edited Jul 28, 2017 at 13:31

Ali

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answered May 6, 2009 at 18:31

Syed Tayyab Ali

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1 Comment

snus74 Over a year ago

this doesnt work. ParametrizedThreadStart requires to use a single argument of type of Object. When using Object[] as a type instead you get the following error: cannot convert from 'method group' to 'parametrizedThreadStart'

mqp · Accepted Answer · 2009-05-06 18:33:37Z

0

You could curry the "work" function with a lambda expression:

public void StartThread()
{
    // ...
    Thread standardTCPServerThread = new Thread(
        () => standardServerThread.Start(/* whatever arguments */));

    standardTCPServerThread.Start();
}

answered May 6, 2009 at 18:33

mqp

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Comments

mcmillab · Accepted Answer · 2014-10-23 23:44:17Z

0

You need to pass a single object, but if it's too much hassle to define your own object for a single use, you can use a Tuple.

answered Oct 23, 2014 at 23:44

mcmillab

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