User FAQs

If you have a question, please send it to us.

1) What is Multi-Threading ?
In a single threaded application there is only one active thread.
In a multi-threaded application you can have two (or more) active threads.
This allows different tasks to be carried out in parallel.
The advantage of a divide and conquer strategy is that it will improve performance.

2) What is the difference between a Process and a Thread ?
Processes are independent, threads are not independent.
Switching between processes is slower than switching between threads.
A process has its own address space, all the threads within a single process all share the same address space.

3) Can you describe the different Thread States ?
Unstarted -
Running -
SleepWaitJoin -
Suspended -
Stopped -

4) What is the difference between a Background Thread and a Foreground Thread ?
Any threads that are explicitly created are foreground threads.
A foreground thread runs indefinitely and will keep the application alive.
A background thread terminates when the foreground thread is stopped and will not keep the application alive.

5) What is displayed when this code runs ?

public main() 
{ 
   Method1() 
   MessageBox.Show("Two"); 
} 

public async void Method1() 
{ 
   thread.wait(10); 
   MessageBox.Show("One"); 
} 

The Method1 is executed on a different thread and this message box will only be displayed after the 10 seconds.
"Two"
"One"

6) What does the ThreadStatic attribute do ?

System.ThreadStaticAttribute 

This is used to indicate a variable is thread safe.
A static variable is not shared between threads.
Each executing thread will have a separate instance of the field and will independently set and get values for that variables.
If the variable is accessed on a different thread, it will contain a different value.

7) What is the Task Parallel Library ?
This replaces the earlier Processor and Thread classes with a new class called Task.
The System.Threading.Tasks namespace has been designed for executing multi-threaded applications on machines that have multiple core processors.
The new Task class has a higher level of abstraction than the Thread.

8) What does the async keyword do ?
Introduced in C# 5.0 (.NET 4.5).

9) What is the difference between Threading.Timer and Timers.Timer ?
They were both added in .NET 1.1