import threading

def f(arg):
    global running
    running += 1
    print("Spawned a thread. running=%s, arg=%s" % (running, arg))
    for i in range(100000):
        pass
    running -= 1
    print("Done")

running = 0
while True:
    if running < 8:
        arg = get_task()
        threading.Thread(target=f, args=[arg]).start()

//C# 
using  System.Threading.Tasks;

void  f(int  arg)
{
   //... 
}

void  main()
{
   var  options = new  ParallelOptions() { MaxDegreeOfParallelism = 8 } ;
   Parallel.For(1, 1000_000, options, f) ;
}

//C# 
using  System.Threading.Tasks;

void  f(int  arg)
{
   //... 
}

void  main()
{
   var  options = new  ParallelOptions() { MaxDegreeOfParallelism = 8 } ;
   var  values = new int  [ ] { 123, 456, 789, 147, 258, 369 /* ...array-items... */  } ;
   Parallel.ForEach(values, options, f) ;
   //the 'values' is a IEnumerable, which means a stream of data of specified/unknown length. ex. array,list,linkedList,queue,stack,dbCursor,...  
}