multithreading - Thread Pool Class developement -

i run multithread application , want limit number of threads on machine code concept goes (it drft show major ideas behind)

     //  list threads have        class mythreadlist = list<tmycalcthread>;      //  pool class, check how many threads active       //  try start additions threads once nr. of running threads      //  below max_thread_value_running      class mytheardpool = class                 threadlist :  mythreadlist;                 stillrunningthreads : integer;                 startfromthreadid : integer;                end;        var athreadlist : mythreadlist;         procedure  mainform.callcreatethreadfunction( < thread params > );       begin             //   create not start here              mythread := tmycalcthread.create ( < thread params > );              mythread.onterminate := what_to_do;               //   add threads list              athreadlist.add(mythread);       end;         /// (a)       procedure  mainform.what_to_do ()        var start : integer;       begin              max_thread_value_running := max_thread_value_running -1;              if max_thread_value_running < max_thread_count                    begin                    start := max_thread_count - max_thread_value_running;                      startthereads(start,startfromthreadid)                   end;       end;        procedure mainform.startthereads (howmany , fromindex : integer);       var    : integer;        begin            := fromindex howmany + fromindexdo                  begin                    //  thread[i].start                 end;       end;          mainform.button ();        ///  main vcl form , create threats       := 0 allthreads              begin                callcreatethreadfunction( < thread params > );              end;        ......       ///  (b)      while  stillrunningthreads > 0              begin                 application.processmessages;              end; 

the complete idea small list threads, on every individual thread terminate step update number of running threads , start possible max. number of new threads.(a) instead of function waitforsingleobject () .... loop @ end wait threads finish execution. (b)

from code design did not find full example on net, may approach vaild design or run trouble did not consider right now. comment on diesign or better class design welcome.

don't try micro-manage threads this. don't. either use win api threadpool calls, or make own threadpool producer-consumer queue , tthread instances.

when task completed, suggest work thread call 'oncompletion' tnotifyevent of task class task parameter. ths can set issuer of task might wish, eg. postmessaging task instance gui thread display.

micro-managing threads, continually creating/waiting/terminating/destroying, application.processmessages loops etc. horrible , sure go wrong @ point.

waiting in gui event-handler bad. gui system state-machine , should not wait inside it. if want issue task gui thread, don't wait - fire off , forget until completed , gets posted message-handler procedure.