C#•7mo ago

✅ Threads in c#

I am wondering if it is possible to kill main thread while other thread is still being executed? Cuz as i know additional threads are being created in the main thread thus killing main threads would mean to stop executing the code but in the screen shot it behaves differently.

15 Replies

Dachi•7mo ago

c#
Temp();

static void Temp()
{
    var main = Thread.CurrentThread;
    RunningThread(main);
}

static void RunningThread(Thread mainThread)
{
    var thread = new Thread(() =>
    {
        while (true)
        {
            Console.WriteLine("Running thread is alive");
            Thread.Sleep(2000);
            Console.WriteLine(mainThread.IsAlive + " is main thread alive");
        }
    });
    thread.Start();
}

c#
Temp();

static void Temp()
{
    var main = Thread.CurrentThread;
    RunningThread(main);
}

static void RunningThread(Thread mainThread)
{
    var thread = new Thread(() =>
    {
        while (true)
        {
            Console.WriteLine("Running thread is alive");
            Thread.Sleep(2000);
            Console.WriteLine(mainThread.IsAlive + " is main thread alive");
        }
    });
    thread.Start();
}

JP•7mo ago

in the screen shot it behaves differently

Can you elaborate here? Differently how? I don't actually know the answer here. Not sure if having child threads prevents killing the main thread from c# land

Dachi•7mo ago

sure by differently i meant that main thread dies But as i know in the stack main thread is the first one, thus it means that main thread has to die last

JP•7mo ago

I can say killing threads outright is generally dangerous I'm going to go see if I can discover what happens w/ main thread kills by fiddling / googling 👀

Dachi•7mo ago

i am not killing it by force. It stops by itself, as code demostrates.

cap5lut•7mo ago

as long as there are any non-background threads running the process continues execution. it doesnt matter if the main thread finished execution earlier

Dachi•7mo ago

So main thread is not that main?

cap5lut•7mo ago

its simply the only thread created at process start, thats it

Dachi•7mo ago

like isn't executing happen like in a stack. First method (main) executes other ones thus it means that at the end when the all other threads end only then main thread dies.

cap5lut•7mo ago

each thread has its own stack

Dachi•7mo ago

ooooh so they're equal in terms of importance? right? like it is not that main thread is the MAIN thread i get it now Thanks

cap5lut•7mo ago

u can easily observe this with the following program:

var mainThread = Thread.CurrentThread;
var secondaryThread = new Thread(() => {
    while (mainThread.IsAlive)
    {
        Thread.Sleep(1);
    }
    Console.WriteLine(mainThread.IsAlive);
});
secondaryThread.IsBackground = false;
secondaryThread.Start();

var mainThread = Thread.CurrentThread;
var secondaryThread = new Thread(() => {
    while (mainThread.IsAlive)
    {
        Thread.Sleep(1);
    }
    Console.WriteLine(mainThread.IsAlive);
});
secondaryThread.IsBackground = false;
secondaryThread.Start();

(note that for some reason this doesnt work on sharplab, nor the bot gives output) but also generally speaking, u shouldnt care too much about threads, especially creating ur own, this is a quite costly operation and using the threadpool/task API instead is most of the time better and just throwing more threads at something doesnt make it faster per se, especially cpu-bound tasks in more threads than you have logical processor threads will most likely slow down the whole thing

Dachi•7mo ago

Sure thanks for clearification

cap5lut•7mo ago

glad i could help o7 if u feel like ur questions are answered, dont forget to $close the thread (pun not intended)

MODiX•7mo ago

Use the /close command to mark a forum thread as answered

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✅ Threads in c#