.net - C# infinitive task loop using Task<> class + cancellation -

i`m trying make small class multithreading usage in winform projects.

tried threads(problems ui), backgroundworker(smth went wrong ui too, leave now:)), trying task class. now, can`t understand, how make infinitive loop , cancelling method (in class) running tasks. examples found used in 1 method.

so, here structure & code of working part (worker.css , methonds used in winform code).

worker.css

class worker {     public static int threadcount { get; set; }      public void dowork(parameterizedthreadstart method)     {         task[] tasks = enumerable.range(0, 4).select(i => task.factory.startnew(() => method(i))).toarray();     } } 

usage on form1.cs

    private void start_btn_click(object sender, eventargs e)     {         worker.threadcount = 1; //actually doesn`t using now, number of tasks declared in class temporaly         worker worker = new worker();         worker.dowork(job);          string logstring_1 = string.format("starting {0} threads...", worker.threadcount);         log(logstring_1);      }      public static int j = 0;     private void job(object sender)     {         worker worker = new worker();         random r = new random();          log("thread "+thread.currentthread.managedthreadid +" working...");         (int = 0; < 5; i++)         {             j++;             log("j==" + j);             if (j == 50)             {                 //worker.stop();                 log("stop");             }         }         thread.sleep(r.next(500, 1000));     } 

so, run example 4 threads, executed, got j==20 in log, it`s ok.

my question is, how implement infinitive loop tasks, created worker.dowork() method. , make .stop() method worker class (which should stop tasks when called). understand it`s related questions, put in 1.

i tryed solutions, of them based on cancellationtoken usage, have create element inside of worker.dowork() method, can`t use same token create worker.stop() method.

someone can help? threads amount range have use in software 5-200 threads. using j computation example of the easy condition used stop software work(stop of tasks/threads). in real, stop conditions queue<> finished, or list<> elements empty(finished).

finally, works.

class worker {     public static int threadcount { get; set; }     task[] tasks;      //ex data     public static string exception;      static cancellationtokensource wtoken = new cancellationtokensource();     cancellationtoken cancellationtoken = wtoken.token;     public void dowork(parameterizedthreadstart method)     {         try         {             tasks = enumerable.range(0, 4).select(i => task.factory.startnew(() =>             {                 while (!cancellationtoken.iscancellationrequested)                 {                     method(i);                 }             }, cancellationtoken)).toarray();         }         catch (exception ex) { exception = ex.message; }     }       public void hardstop()     {         try         {             using (wtoken)             {               wtoken.cancel();             }             wtoken = null;             tasks = null;         }         catch (exception ex) { exception = ex.message; }     } } 

but if i`m using method quit cancellationtoken.throwifcancellationrequested(); error: when job() method reach j == 50, , worker.hardstop() function called, program window crashes , , exception "oparetioncanceledexception unhandled user code" on string

cancellationtoken.throwifcancellationrequested(); 

so, whats wrong? i`m put in try{} catch(){} understood, boolean properties should changed in task (task.iscancelled == false, task.isfaulted == true) on wtoken.cancel();