Remove defensive Task[] copy from non-generic Task.WhenAll #81065
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
When calling it with a `Task[]` or `List<Task>`, we'll no longer generate a temporary array; the only allocation in those cases will be for the returned Task itself, at least if it completes successfully (if multiple of the constituent tasks fail or are canceled, we'll end up with an additional list allocation beyond what we had before). If you call it with an enumerable that's not an `ICollection<Task>`, we'll also save a `Task[]`.
ghost
assigned 
|
Tagging subscribers to this area: @dotnet/area-system-threading-tasks Issue DetailsWhen calling it with a Contributes to #77873
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
[MemoryDiagnoser(false)]
public partial class Program
{
static void Main(string[] args) => BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);
[Benchmark]
public void WhenAll_Array()
{
AsyncTaskMethodBuilder atmb1 = AsyncTaskMethodBuilder.Create();
AsyncTaskMethodBuilder atmb2 = AsyncTaskMethodBuilder.Create();
Task whenAll = Task.WhenAll(atmb1.Task, atmb2.Task);
atmb1.SetResult();
atmb2.SetResult();
whenAll.Wait();
}
[Benchmark]
public void WhenAll_List()
{
AsyncTaskMethodBuilder atmb1 = AsyncTaskMethodBuilder.Create();
AsyncTaskMethodBuilder atmb2 = AsyncTaskMethodBuilder.Create();
Task whenAll = Task.WhenAll(new List<Task>(2) { atmb1.Task, atmb2.Task });
atmb1.SetResult();
atmb2.SetResult();
whenAll.Wait();
}
[Benchmark]
public void WhenAll_Collection()
{
AsyncTaskMethodBuilder atmb1 = AsyncTaskMethodBuilder.Create();
AsyncTaskMethodBuilder atmb2 = AsyncTaskMethodBuilder.Create();
Task whenAll = Task.WhenAll(new ReadOnlyCollection<Task>(new[] { atmb1.Task, atmb2.Task }));
atmb1.SetResult();
atmb2.SetResult();
whenAll.Wait();
}
[Benchmark]
public void WhenAll_Enumerable()
{
AsyncTaskMethodBuilder atmb1 = AsyncTaskMethodBuilder.Create();
AsyncTaskMethodBuilder atmb2 = AsyncTaskMethodBuilder.Create();
var q = new Queue<Task>(2);
q.Enqueue(atmb1.Task);
q.Enqueue(atmb2.Task);
Task whenAll = Task.WhenAll(q);
atmb1.SetResult();
atmb2.SetResult();
whenAll.Wait();
}
}
|
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
When calling it with a
Task[]orList<Task>, we'll no longer generate a temporary array; the only allocation in those cases will be for the returned Task itself, at least if it completes successfully (if multiple of the constituent tasks fail or are canceled, we'll end up with an additional list allocation beyond what we had before). If you call it with an enumerable that's not anICollection<Task>, we'll also save aTask[].Contributes to #77873