task-parallel-library

问题 I'm developing a Xamarin Forms mobile app, which has a page containing a SearchBar, a ListView, and Map control. The list view contains a list of addresses, which are reflected as pins on the map. As the user types in the SearchBar, the ListView is automatically updated (through ViewModel binding). The ViewModel method that filters the datasource for the list looks something like this... void FilterList() { listDataSource = new ObservableCollection<location>( locationData.Where(l => l.Address

问题 ParallelEnumerable has a static member AsParallel . If I have an IEnumerable<T> and want to use Parallel.ForEach does that imply that I should always be using AsParallel ? e.g. Are both of these correct (everything else being equal)? without AsParallel : List<string> list = new List<string>(); Parallel.ForEach<string>(GetFileList().Where(file => reader.Match(file)), f => list.Add(f)); or with AsParallel ? List<string> list = new List<string>(); Parallel.ForEach<string>(GetFileList().Where

问题 ParallelEnumerable has a static member AsParallel . If I have an IEnumerable<T> and want to use Parallel.ForEach does that imply that I should always be using AsParallel ? e.g. Are both of these correct (everything else being equal)? without AsParallel : List<string> list = new List<string>(); Parallel.ForEach<string>(GetFileList().Where(file => reader.Match(file)), f => list.Add(f)); or with AsParallel ? List<string> list = new List<string>(); Parallel.ForEach<string>(GetFileList().Where

问题 I've asserted my understanding of async/await on a couple of occasions, often with some debate as to whether or not I'm correct. I'd really appreciate it if anyone could either confirm or deny my understanding, and clear up any misconceptions so that I don't spread misinformation. High-Level Understanding async / await is a way of avoiding callback hell while writing asynchronous code. A thread that is executing an asynchronous method will return to the thread pool when it encounters an await

问题 I am really curious how async/await enables your program not to be halted. I really like the way how Stephen Cleary explains async/await: "I like to think of "await" as an "asynchronous wait". That is to say, the async method pauses until the awaitable is complete(so it waits), but the actual thread is not blocked (so it's asynchornous)." I've read that async method works synchronously till compilator meets await keywords. Well. If compilator cannot figure out awaitable, then compilator

问题 (Sticking to a common example with async fetch of many web pages) How would I spin off multiple (hundreds) of web page requests asynchronously, and then wait for all requests to complete before going to the next step? Async.AsParallel processes a few requests at a time, controlled by number of cores on the CPU. Grabbing a web page is not a CPU-bound operation. Not satisfied with the speedup of Async.AsParallel, I am looking for alternatives. I tried to connect the dots between Async

问题 Today we deployed our newly created ASP.NET application to the server and soon we realized there was a strange security-related issue which was causing the application to crash. This is an internal application and we use Impersonation to manage how the users access resources. The application however, throws an "Access Denied" exception when the user attemps to access a folder over which they have full control. The exception was in fact an AggregateException and was being thrown in a method

问题 I read that PLinq will automatically use non parallel Linq if it finds PLinq to be more expensive. So I figured then why not use PLinq for everything (when possible) and let the runtime decide which one to use. The apps will be deployed to multicore servers and I am OK to develop a little more code to deal with parallelism. What are the pitfalls of using plinq as a default? 回答1: One pit fall is you lose the ability to leverage ordering in sets. Take the following code: var results = new int {

问题 I read that PLinq will automatically use non parallel Linq if it finds PLinq to be more expensive. So I figured then why not use PLinq for everything (when possible) and let the runtime decide which one to use. The apps will be deployed to multicore servers and I am OK to develop a little more code to deal with parallelism. What are the pitfalls of using plinq as a default? 回答1: One pit fall is you lose the ability to leverage ordering in sets. Take the following code: var results = new int {

问题 I have a quantifiable & repeatable problem using the Task Parallel Library, BlockingCollection<T> , ConcurrentQueue<T> & GetConsumingEnumerable while trying to create a simple pipeline. In a nutshell, adding entries to a default BlockingCollection<T> (which under the hood is relying on a ConcurrentQueue<T> ) from one thread, does not guarantee that they will be popped off the BlockingCollection<T> from another thread calling the GetConsumingEnumerable() Method. I've created a very simple