Regarding background or foreground thread in C#

Question

i like to know what is background thread and what is foreground thread ?
how they are different ?
which one we should always use?
threads are by default background or foreground ?
the new Task Parallel Library use thread class or is it totally different one?
what kind of thread TPL used background or foreground ?
how TPL is different from normal thread class and ThreadPool.QueueUserWorkItem ?
looking for discussion in details with sample code. thanks

Answer 1

Background threads are identical to foreground threads with one exception: a background thread does not keep the managed execution environment running. Once all foreground threads have been stopped in a managed process (where the .exe file is a managed assembly),
the system stops all background threads and shuts down:
https://msdn.microsoft.com/en-us/library/h339syd0%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396
>>the new Task Parallel Library use thread class or is it totally different one?
A Task resembles a thread but at a higher level of abstraction. Please refer to Jon Skeet's answer in the following thread for more information:
http://stackoverflow.com/questions/13429129/task-vs-thread-differences.
It is recommended to use the higher level abstraction (Task) wherever you can. You rarely need to explicitly start your own thread in C# 4 or later.
>>what kind of thread TPL used background or foreground ?
Background. When you create a Task, it is the responsibility of a TaskScheduler to ensure that the work of the task is eventually executed. The default TaskScheduler uses the ThreadPool under the hood to queue and execute work:
https://msdn.microsoft.com/en-us/library/dd997402(v=vs.110).aspx. And the ThreadPool creates background threads.
>>how TPL is different from normal thread class and ThreadPool.QueueUserWorkItem ?
The TPL has the advantage of being able to hook into internals of the ThreadPool that are not exposed publicly and that can boost performance in a variety of key scenarios. It scales the degree of concurrency dynamically to most efficiently use all the processors
that are available for you.
Please refer to the following MSDN blog post for more information:
http://blogs.msdn.com/b/pfxteam/archive/2009/10/06/9903475.aspx
Please only ask ONE question per thread and please remember to close your thread by marking helpful posts as answer and then start a new thread if you have a new question.