任务并行库执行长时间运行的操作

Question

Is it a good approach to use Task (Task Parallel Library) to perform long running operations (sometimes can take few hours to complete)?

In one of the stack overflow threads I saw one person telling not to use Threadpool if the long running operations take more than few seconds to complete. I have such a doubt since Task also uses the ThreadPool under the hood, in order to distribute the work, without going through the overhead of Thread creation/or un-necessary context switching.

Answer 1

As long as you keep a foreground thread alive, using a task is OK - just be sure to specify the TaskCreationOptions.LongRunning option to prevent thread starvation if you are running a lot of concurrent tasks.

The below simple console application demonstrates how the lack of a foreground thread will terminate the "long running thread" prematurely as the process ends.

class Program
{
    static void Main( string[] args )
    {
        Task.Factory.StartNew( () =>
            {
                Console.WriteLine( "Before sleep" );
                System.Threading.Thread.Sleep( 5000 );
                Console.WriteLine( "After sleep" );
            }
            , TaskCreationOptions.LongRunning
            );

        // press a key prior to the 5 second sleep expiration to demonstrate early termination
        Console.ReadKey();
    }
}