Task.WaitAll Method (Task, Int32)
Waits for all of the provided Task objects to complete execution within a specified number of milliseconds.
Assemblies: System.Threading.Tasks (in System.Threading.Tasks.dll)
mscorlib (in mscorlib.dll)
One or more of the Task objects in tasks has been disposed.
The tasks argument is null.
An exception was thrown during the execution of at least one of the Task instances.
millisecondsTimeout is a negative number other than -1, which represents an infinite time-out.
The tasks argument contains a null element.