task-parallel-library

问题 I'm trying to implement an algorithm that should run in parallel using threads or tasks. The difficulty is that I want the threads/tasks to share their best results from time to time with all other threads. The basic idea is this: //Accessible from each thread IProducerConsumerCollection<MyObject> _bestObjects; //Executed in each thread DoSomeWork(int n){ MyObject localObject; for(var i = 0; i < n; i++){ //Do some calculations and store results in localObject if((i/n)%0.5 == 0) { //store

问题 So i have a large file which has ~2 million lines. The file reading is a bottleneck in my code. Any suggested ways and expert opinion to read the file faster is welcome. Order of reading lines from that text file is unimportant. All lines are pipe '|' separated fixed length records. What i tried? I started parallel StreamReader s and made sure that resource is locked properly but this approach failed as i now had multiple threads fighting to get hold of the single StreamReader and wasting

问题 I want to download webPages content of url list (10 000 urls). Is httpCLient the fastest and cleanest way (instead httpwebrequest, or webclient)? If I want to be fast, Is TPL the best way ? I'm looking for something like, but really fast and clean (10 000 request) ? public List<string> GetContentListOfUrlList(List<Uri> uriList, int maxSimultaneousRequest) { //requesting url by the fastest way } I hope is better like this ;) EDIT 2 : According to noseratio other post Is the best solution ?

问题 I have a windows C# WinForms application. I'm confused by the way the default task scheduler is behaving for parallel class in task parallel library. When I call Parallel.For inside ParallelForEach method I was expecting the numbers to get printed in jumbled fashion in output window through Console.WriteLine statement inside "Method1" method. Since I'm not passing any ParallelOptions to configure the scheduler for Parallel class it should be using default task scheduler but numbers are

问题 Assume we have an array of tasks (called 'tasks') and then convert it to a list (called 'temp') by saying: var temp = tasks.ToList(); What happens to those running tasks to which the array elements point? Do we have two sets of tasks running separately (one in the 'tasks' and the other in 'temp')? Or they point to the same tasks? The following code (taken from the book Exam Ref 70-483 ) is relevant to what I'm saying (the last three lines): Task<int>[] tasks = new Task<int>[3]; tasks[0] =

问题 This code is from Microsoft article http://msdn.microsoft.com/en-us/library/dd460703.aspx, with small changes: const int size = 10000000; int[] nums = new int[size]; Parallel.For(0, size, i => {nums[i] = 1;}); long total = 0; Parallel.For<long>( 0, size, () => 0, (j, loop, subtotal) => { return subtotal + nums[j]; }, (x) => Interlocked.Add(ref total, x) ); if (total != size) { Console.WriteLine("Error"); } Non-parallel loop version is: for (int i = 0; i < size; ++i) { total += nums[i]; } When

问题 This code is from Microsoft article http://msdn.microsoft.com/en-us/library/dd460703.aspx, with small changes: const int size = 10000000; int[] nums = new int[size]; Parallel.For(0, size, i => {nums[i] = 1;}); long total = 0; Parallel.For<long>( 0, size, () => 0, (j, loop, subtotal) => { return subtotal + nums[j]; }, (x) => Interlocked.Add(ref total, x) ); if (total != size) { Console.WriteLine("Error"); } Non-parallel loop version is: for (int i = 0; i < size; ++i) { total += nums[i]; } When

问题 I have a function that looks something like the code below. Its purpose is to take triangle facets one at a time from an array of points where each three points is one facet, and tessellate them, replacing the facet with a list of smaller facets whose side lengths don't exceed nodeSize. Naturally, this function is time consuming for any realistic facet mesh. I'd like to refactor it to use some coarse parallelization. However, Parallel.For doesn't appear to have a way to step through indices

问题 Consider a piece of code like: private Task<string> Download() { var wc = new WebClient(); Task<string> backgroundDownload = wc.DownloadStringTaskAsync(this.Uri); // Make sure the WebClient is disposed no matter what. backgroundDownload.ContinueWith((downloadTask) => { wc.Dispose(); }); return backgroundDownload; } Can I be certain that the WebClient.Dispose() call occurs and that any exception produced is rethrown to the caller as if there was no call to ContinueWith ? Can clients observe

问题 I am trying to wrap the exceptions that can be thrown by an async task using ContinueWith() . If I just throw from the continuation action things seem to work, but my debugger claims the exception is unhandled. Am I doing something wrong or is this a Visual Studio problem? Is there a cleaner way to do this, or a way to work around my debugger stopping on what is ultimately a handled exception? The test below passes and prints "caught wrapped exception as expected", but when I debug it the