Pausing a Thread Safely

In .Net you have the option of Thread.Suspend() and Thread.Abort(), but under normal circumstances these are horrible options to use because they’re likely to create locking problems (i.e., the thread has a locks on resource that other threads need).

A far better way is to signal to the thread that it should pause and wait for a signal to continue.  Sometimes it can be as simple as setting a boolean value where both threads can see it. Or you could wrap the boolean value in a property and protect it with a lock, but this is probably overkill for most applications.

To pause a thread safely requires you to use a blocking signal mechanism and .Net has ManualResetEvent for just this purpose.

You could then have some C# code like this:

ManualResetEvent pauseEvent = new ManualResetEvent();

//Thread A (Controlling thread)
void OnPause()
{
 pauseEvent.Reset();
}

void OnStart()
{
pauseEvent.Set();
}

//Thread B (the one to pause)
void ThreadFunction()
{
while(doWork == true)
 {
 //do work
 …
 …

 //wait until event is set
 pauseEvent.WaitOne();
 }
}

This way, you can safely pause work and continue it at a later time, safely avoiding the possibility of deadlocks*.

* Actually, it’s still possible to create a resource locking problem–make sure you release any shared resource locks before pausing.

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