multithreading - .NET - Block main thread until there are any available threads -

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i have process main thread reading file , splitting parts. parts require further processing. utilize available threads downstream processing utilizing cpu (or many cores) possible. don't want create excessive backlog main thread, need main thread wait add queue until there available thread.

i see many articles vb.net 4.0: looking execute multiple threads, wait until threads completed before resuming, waiting all threads complete, whereas need any threads available

is can tackle task parallel library, or should manually creating threads , monitoring threadpool?

using reader new streamreader(filename)             currentblocksize = reader.readblock(currentbuffer, 0, buffersize)          runningbuffer &= new string(currentbuffer)          if runningbuffer.contains(rowdelimiter)             lineparts = runningbuffer.split(rowdelimiter)              integer = 0 lineparts.count - 1                 if < lineparts.count - 1                      'make synchronous call blocks until'                      'another thread available process line'                     addlinetotheprocessingqueue(currentline)                  else                     runningbuffer = lineparts(i)                 end if             next         end if      loop while currentblocksize = buffersize end using

paste code new console application. 

imports system.threading  module module1      ' picked 6 randomly, not sure strategy picking number     ' also, not sure difference between worker thread , completion thread     const maxworkerthreads integer = 6     const maxcompletionportthreads integer = 6      sub main()          threadpool.setmaxthreads(maxworkerthreads, maxcompletionportthreads)          dim availableworkerthreads integer         dim availablecompletionportthreads integer          integer = 0 100              ' getavailablethreads returns results via output parameters             threadpool.getavailablethreads(availableworkerthreads, availablecompletionportthreads)              dim tries integer = 0              while (availableworkerthreads = 0)                 ' loop not execute if there available threads                 ' may want add fail-safe check "tries" in case child threads stuck                 tries += 1                  console.writeline(string.format("waiting start item {0}, attempt {1}, available threads: {2}, {3}", i, tries, availableworkerthreads, availablecompletionportthreads))                  ' failure call sleep make program unresponsive                 thread.sleep(1000)                  ' call getavailablethreads again next test @ top of loop                 threadpool.getavailablethreads(availableworkerthreads, availablecompletionportthreads)             loop              ' how pass parameters thread created through queueuserworkitem             dim parameters object() = {i}             threadpool.queueuserworkitem(addressof dowork, parameters)             ' according msdn, must sleep after calling queueuserworkitem, or else current thread exit             thread.sleep(500)          next      end sub      sub dowork(parameters object())         dim itemnumber = parameters(0)         dim sleeplength = itemnumber * 1000         console.writeline(string.format("item: {0} - sleeping {1} miliseconds.", itemnumber, sleeplength))         thread.sleep(sleeplength)         console.writeline(string.format("item: {0} - done sleeping.", itemnumber))     end sub  end module

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