What are alternative ways to suspend and resume a thread?

Question

The two methods Thread.Suspend() and Thread.Resume() are obsolete since .NET 2.0. Why? What are other alternatives and any examples?

Answer 1

You'll want to use an AutoResetEvent EventWaitHandle.

Say you want to do something like this (NOTE: don't do this!):

private Thread myThread;

private void WorkerThread() 
{
    myThread = Thread.CurrentThread;
    while (true)
    {
        myThread.Suspend();
        //Do work.
    }
}

public void StartWorking() 
{
    myThread.Resume();
}

Like others have said, this is a bad idea. Even though only using Suspend on its own thread is relatively safe, you can never figure out if you're calling Resume when the thread is actually suspended. So Suspend and Resume have been obsoleted.

Instead, you want to use an AutoResetEvent:

private EventWaitHandle wh = new AutoResetEvent();

private void WorkerThread() 
{
    while(true) 
    {
        wh.WaitOne();
        //Do work.
    }
}

public void StartWorking()
{
    wh.Set();
}

The worker thread will wait on the wait handle until another thread calls StartWorking. It works much the same as Suspend/Resume, as the AutoResetEvent only allows one thread to be "resumed".