Basic thread polling code in C#

I need someone familiar with threads and thread polling in C# to write some pretty basic piece of code for me. There's a Form with a multiline TextBox, a Button and a StatusBar. User enters a few lines of text in the TextBox and clicks the Button. For each line in the TextBox I need a foo(line) method to be called BUT I want this to be done in multiple threads (max number of threads running at once should be hard-coded). Each thread should also increment a global counter variable / property of Form1 class (you need to be familiar with data monitoring/locking so that the value doesn't get wrong) and update the statusbar text with its value when it's finished. Basically, I need the following pseudocode translated into working C#: foreach(line in textbox) { if(number_of_running_threads == max_number_of_threads) { wait_until_there_is_a_free_thread(); } run_in_thread( foo(line) ); } You can leave the foo() body empty or put some random sleep() there or whatever. For an experienced C# dev this shouldn't take longer than an hour.