C# Waiting for Thread to finish

Question

I want to run 10 threads on the same time and want to start a new one, if one is completed. So example: I create 10 Threads. If the 1. is finished, i want to start a new one, but i want to hold a maximum value of threads of 10.

How can i realize this?

I've tried it like this:

 for (int z = 0; z < 10; z++)
            {
                Thread t = new Thread(() => check(name)); T.Start();


                if (z == 9)
                {
                    z = 0;
                }

            }

The Problem is here, that the program doesnt wait for the Threads to finish. How can i realize it here?

Thanks!

why let your threads finish, just have 10 threads and have them loop inside of themselves to pull from a common work pool. — Scott Chamberlain, Jun 01 '17 at 21:39
Are you basically saying "I want an array of 10 but will ever use only one"? — Camilo Terevinto, Jun 01 '17 at 21:59
no i want to run permanently 10 threads. if one thread is finished, i want to replace it with another one. — Brandon Baba, Jun 01 '17 at 22:04
These days, thinking in terms of threads is the opposite of what you should be doing. Thing in terms of asynchronous tasks instead (which can occur on a single thread a lot of the time) — Joe Phillips, Jun 01 '17 at 22:11
Consider trying Parallel.ForEach - https://dotnetfiddle.net/XHNSIJ — mjwills, Jun 01 '17 at 23:18

score 1 · Answer 1 · answered Jun 01 '17 at 21:51

First of all, it is better to avoid creating threads explicitly unless you are absolutely sure you know what you are doing (Thread resources are limited and thread object on its own quite heavyweight). In all the other cases prefer Task (or at least ThreadPool). For tasks you can use Task.WhenAll(array of tasks) method to wait for all the required tasks completion before resuming main execution flow.

But if for some reason you still need to use Thread class, you can use Thread.Join(thread) method to block executing thread and wait for all required threads to finish their jobs.:

foreach (var thread in jobThreads)
{
    thread.Join();
}

hey, thanks for answering. but if i use Thread.Join(); my application just creates 1 Thread.. do you know my fail? :/ — Brandon Baba, Jun 01 '17 at 22:00

score 0 · Answer 2 · answered Jun 01 '17 at 21:39

0

search for Thread.Join:

"Blocks the calling thread until the thread represented by this instance terminates".

for (Thread t : threads) {
  t.join();
}

you can block multiple threads waiting for 1 thread.

answered Jun 01 '17 at 21:39

Gabri T

454
2
13

If i use Thread.Join(); my application just create 1 Thread. – Brandon Baba Jun 01 '17 at 21:43
that actually doesn´t happen. check this link from MSDN: *https://msdn.microsoft.com/en-us/library/95hbf2ta(v=vs.110).aspx* – Gabri T Jun 01 '17 at 22:10

C# Waiting for Thread to finish

2 Answers2