Thread Safety of WeakReference

Question

When using a WeakReference, how can we be sure than the target is not collected between the .IsAlive and .Target calls?

For example:

if (myWeakReference.IsAlive)
{
    // How can we be sure the object is still alive while here?
    ((MyType)myWeakReference.Target).Foo();
}

Answer 1

Just get the Target and check whether it's not null:

object target = myWeakReference.Target;
if (target != null)
{        
    ((MyType)target).Foo();
}

The docs for IsAlive specifically say:

Because an object could potentially be reclaimed for garbage collection immediately after the IsAlive property returns true, using this property is not recommended unless you are testing only for a false return value.

Answer 2

You can't. Assign myWeakReference.Target to a variable, and check for null.