All Questions
Tagged with .net-4.5 asynchronous
131
questions
722
votes
6
answers
587k
views
async/await - when to return a Task vs void?
Under what scenarios would one want to use
public async Task AsyncMethod(int num)
instead of
public async void AsyncMethod(int num)
The only scenario that I can think of is if you need the task ...
- 9,032
155
votes
2
answers
168k
views
How does Task<int> become an int?
We have this method:
async Task<int> AccessTheWebAsync()
{
HttpClient client = new HttpClient();
Task<string> getStringTask = client.GetStringAsync("http://msdn.microsoft.com");
...
- 5,741
149
votes
6
answers
199k
views
Run two async tasks in parallel and collect results in .NET 4.5
I've been trying for a while to get something I thought would be simple working with .NET 4.5
I want to fire off two long running tasks at same time and collect the
results in in the best C# 4.5 (...
- 143k
132
votes
3
answers
48k
views
Is async HttpClient from .Net 4.5 a bad choice for intensive load applications?
I recently created a simple application for testing the HTTP call throughput that can be generated in an asynchronous manner vs a classical multithreaded approach.
The application is a able to ...
- 8,212
57
votes
10
answers
56k
views
awaitable Task based queue
I'm wondering if there exists an implementation/wrapper for ConcurrentQueue, similar to BlockingCollection where taking from the collection does not block, but is instead asynchronous and will cause ...
- 119k
33
votes
2
answers
10k
views
Custom awaitables for dummies
In Async/Await FAQ, Stephen Toub says:
An awaitable is any type that exposes a GetAwaiter method which returns a valid awaiter.
...
An awaiter is any type returned from an awaitable’s ...
- 7,185
32
votes
2
answers
24k
views
.NET 4.5 file read performance sync vs async
We're trying to measure the performance between reading a series of files using sync methods vs async. Was expecting to have about the same time between the two but turns out using async is about 5.5x ...
- 403
32
votes
2
answers
45k
views
"await" doesn't wait for the completion of call
I'm building a Metro App.
In the MainPage.xaml.cs, I instantiate Album as follows:
Album album = new Album(2012); //With the album ID as its parameter.
ListView1.ItemsSource = album.Songs;
In the ...
- 1,718
30
votes
5
answers
59k
views
HttpClient is not found in .NET 4.5
I am trying to use the new HttpClient in .NET 4.5, but Visual Studio complains that it doesn't exist. I have System.Net, but when I type System.Net.Http, it complains for that too.
Am I supposed to ...
- 323k
30
votes
4
answers
8k
views
.NET 4.5 async await and overloaded methods
I have an async method:
public async Task<UserLoginExResult> LoginExAsync(CustomTable exRequest, string language, bool throwEx = true)
{
UserLoginExResult result = await UserService....
- 829
24
votes
3
answers
26k
views
Task status changes to RanToCompletion if the Task await's something
The question describes the same problem found here - MSDN Developer Forum. The question does not have an accepted answer, neither any of the answers given can be applied to my case (hence a different ...
- 13.3k
24
votes
1
answer
6k
views
what is the main difference between .net Async and google go light weight thread
When calling runtime.GOMAXPROCS(1) in go the runtime will only use one thread for all your goroutines. When doing io your goroutines will yield and let the other goroutines run on the same thread.
...
- 2,876
22
votes
2
answers
32k
views
Using async / await with DataReader ? ( without middle buffers!)
My goal is simple , I want to do Asynchronous I/O calls (using async await) - but :
Without using DataFlow dependency ( like in this answer)
Without middle buffers( not like this answer)
The ...
- 147k
16
votes
3
answers
9k
views
MVC4 + async/await + return response before action completes
In my MVC4 app I need to add a controller for uploading and processing large files. Immediately after the file is uploaded I need to start async processing of that file and return response to the ...
- 1,475
16
votes
3
answers
14k
views
C# have async function call synchronous function or synchronous function call async function
I'm writing a C# .Net 4.5 library for doing common sql database operations (backup, restore, execute script, etc.). I want to have both synchronous and asynchronous functions for each operation, as ...
- 23.4k
15
votes
1
answer
10k
views
Why do I have to use await for a method to run asynchronously. What if I don't want to wait for the method to finish before continuing? [duplicate]
I've been pouring through MSDN docs all day, and their philosophy of asynchronous coding is confusing me. As I understand it, the thread that calls the async method will not be blocked if the async ...
- 429
12
votes
4
answers
13k
views
Cancel C# 4.5 TcpClient ReadAsync by timeout
What would be the proper way to cancel TcpClient ReadAsync operation by timeout and catch this timeout event in .NET 4.5?
TcpClient.ReadTimeout seems to be applied to the sync Read only.
UPDATE:
Tried ...
- 189
12
votes
3
answers
21k
views
How to use Task.WhenAll() correctly
I am trying to use Task.WhenAll to await completion of multiple tasks.
My code is below - it is supposed to launch multiple async tasks, each of which retrieves a bus route and then adds them to a ...
- 3,948
12
votes
2
answers
8k
views
Dangling await and possible memory leaks in async programming
The flow containing await in .NET 4.5 and Async CTP 4.0 can be stuck due to various reasons, e.g. since the remote client has not responded.
Of course, WaitForAny, when we wait also for some timeout ...
- 283
10
votes
1
answer
5k
views
Exception handling in fire and forget for C# 5 (in .net 4.5)
Consider the following "fire-and-forget" use case:
A caller requests some data from my method. My method checks the cache to see if the data is already there. If it's not, it fetches it from the ...
- 1,188
8
votes
3
answers
1k
views
C# Concurrency - Preferred approach to long running tasks
When there needs to be an I/O listener running throughout an applications lifetime, what concurrency model is preferred with C# 5.0 running on the 4.5 framework?
I've settled on the idea that a ...
- 2,223
7
votes
3
answers
6k
views
async/await. Where is continuation of awaitable part of method performed?
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 ...
- 37.3k
7
votes
2
answers
3k
views
Call Async Method from Session_Start
How can I call an async method from Session_Start in Global.asax ?
Global.asax:
protected async Task Session_Start(object sender, EventArgs e)
{
Session.Timeout = 10;
...
- 3,622
7
votes
1
answer
4k
views
WCF / svcutil in .NET 4.5 generates unusable code by default
With .NET 4.5, my WCF creation using svcutil suddenly seems to break (I've been using only .NET 4.0 until very recently) ....
With the default settings I'm using to convert a pre-existing WSDL to my ...
- 743k
7
votes
3
answers
4k
views
How to unit test RelayCommand that Executes an async method?
As there is no RelayCommandAsync (at least not that I know of), how to test this scenario. For example:
public RelayCommand LoadJobCommand
{
get
{
return this.loadJobCommand ?? (
...
- 11.2k
6
votes
4
answers
12k
views
How do I create a Task that uses await inside the body that behaves the same as the synchronous version when Wait is called?
I have some code that creates a task that does some slow work like this:
public static Task wait1()
{
return new Task(() =>
{
Console.WriteLine("Waiting...");
Thread.Sleep(...
- 41.2k
6
votes
1
answer
7k
views
Async friendly DispatcherTimer wrapper/subclass
I have a DispatcherTimer running in my code that fire every 30 seconds to update system status from the server. The timer fires in the client even if I'm debugging my server code so if I've been ...
- 143k
6
votes
2
answers
7k
views
Async task does not end
I'm trying to start async task (on .NET 4.5) which downloads content of web page, but somehow this task never finishes.
My PageDownloader class:
using System.Net;
using System.Text;
using System.IO;
...
- 4,133
6
votes
2
answers
3k
views
Task.ContinueWith confusion
With ASP.NET 4.5 I'm trying to play with the new async/await toys. I have a IDataReader-implementing class that wraps a vendor-specific reader (like SqlDatareader). I have a simple ExecuteSql() method ...
- 19.6k
6
votes
5
answers
4k
views
Binding and Async Operations
I have created a Window with a TextBlock inside. I have bound the Text property and everything works fine.
BUT
When I change the bounded property while inside a Task then nothing works!!
Do you know ...
6
votes
1
answer
3k
views
Should I upgrade to be able to use the new async methods for SqlDataReader?
I'm working on a large project that runs on .NET 4.0. This framework uses ADO.NET for database calls and we're currently adding asynchronous API methods. The SqlCommand class has the APM methods ...
- 1,596
6
votes
2
answers
636
views
parallel event subscriber .net 4.5
I am trying to create a parallel event subscriber. This is my first attempt:
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using EventStore.ClientAPI;
namespace ...
- 17.1k
6
votes
1
answer
5k
views
Much memory fragmentation with System.Threading.OverlappedData (async await)
I'm constantly running slowly out of memory. I've used WinDbg to have a look at the memory dump and this it what it looks like:
000007f975ee0630 557377 41027736 System.Object[]
000007f975f004d0 ...
- 1,130
5
votes
2
answers
7k
views
HttpClient (C#) fails on many asynchronous requests?
I'm using HttpClient to asynchronously make many requests to an external api. I wait for all the requests to complete, then use the responses in other code. My problem is that if I make too many ...
- 203
5
votes
1
answer
5k
views
Async method in Global.asax
I have to call some async methods in the Application_PostAcquireRequestState method of my Global.asax (these methods comes from a library and there's no equivalent sync method for these operations). I ...
- 2,140
5
votes
1
answer
2k
views
Task continuations always run even when specifying TaskContinuationOptions
I want to run some code when an async task completes successfully.
From reading documentation and examples on the web, I thought I could use Task.ContinueWith and specify TaskContinuationOptions....
- 5,890
5
votes
4
answers
2k
views
How to make Sequential Processing as simple as Parallel Processing
I've got two .net Task objects that I may wish to run in parellel or in sequence. In either case, I don't want to block a thread to wait for them. As it turns out, Reactive Extensions make the ...
- 29.7k
5
votes
2
answers
2k
views
C# async file transfer - waiting before continuing loop
I am trying to get my head around the changes in .NET 4.5, mainly the async features. To get my head around it I thought i would create a little app for archiving my massive photo collection. I learn ...
- 4,577
5
votes
1
answer
2k
views
Running external processes asynchronously in a windows service
I am writing a program that moves csv files from a "queue" folder to a "processing" folder, then a third party process called import.exe is launched taking the csv file path as an argument. Import.exe ...
- 772
4
votes
2
answers
6k
views
return Task.ContinueWith<TResult>() without knowing TResult
How do I create and return a continuation Task using reflection or by any other means if I only have access the Task?
I need a way to let an exception in the continuation travel back to the original ...
- 267
4
votes
1
answer
960
views
BeginExecuteReader, EndExecuteReader and multiple results
I have method that is asynchronously getting results form my database:
internal class CommandAndCallback<TCallback, TError>
{
public SqlCommand Sql { get; set; }
public TCallback ...
- 4,857
4
votes
2
answers
1k
views
Async design pattern - which one is better? [closed]
I've started wondering for asynchronous programming should I always use following pattern:
public async Task<int> MyMethodAsync()
{
return await SomeOtherMethodAsync();
}
or is it safe and ...
- 3,252
4
votes
1
answer
3k
views
Calling async method and TaskScheduler in async/await
Consider the following code
async Task<int> foo()
{
await Task.Delay(1000);
return 42;
}
...
// OPTION 1
Task t = Task.Factory.StartNew(foo,
CancellationToken.None, ...
- 1,333
4
votes
1
answer
2k
views
Why doesn't my Task.ContinueWith execute in .NET 4.5?
Consider the following code
Task<T>.Factory.StartNew(() =>
{
// block #1: load some data from local file cache
}
)
.ContinueWith(task =>
{
// block #2: ...
- 942
3
votes
2
answers
2k
views
create an async method that wraps subscribe and publish on a bus
I have a kind of bus that implements this interface:
public interface IBus
{
void Publish<T>(T t);
void Subscribe<T>(Guid subscriptionId, Action<T> action);
void ...
- 353
3
votes
2
answers
8k
views
How do I create a callback in C# (.NET 4.5) for HttpClient.GetAsync(URI)?
I'd like to create a simple, async request to Google search.
According to Google, the simplest way to do this is using their JSON API with the simple curl request
curl -e http://www.my-ajax-site.com ...
- 1,414
3
votes
2
answers
5k
views
How to implement Command Pattern with async/await
i'm currently upgrading some existing code for use by windows universal and am struggling to convert a command pattern to work with the new async/await functionality.
I have a command scheduler class ...
- 342
3
votes
1
answer
4k
views
C#5 async method completed event.
I have an asynchronous method like this
public async void Method()
{
await // Long run method
}
When Im calling this method can I have a event when this Method completed?
public void CallMethod(...
- 2,868
3
votes
1
answer
2k
views
Unresponsiveness with async event handlers in WPF in .NET 4.5
I have created a simple async operation which is being kicked of when the button is clicked. Here is the whole code:
public partial class MainWindow : Window {
public MainWindow() {
...
- 58.1k
3
votes
1
answer
1k
views
Wait for IProgress Report Method to Return
I am updating my UI via IProgress and the Report method. I do something like
IProgress<ProgressInfo> p = new Progress<ProgressInfo>(ReportProgress);
Task task = Task.Factory.StartNew(() =...
- 23.5k