A .NET utility library for running async methods in parallel batches.

Available on NuGet: and GitHub:

On the side, working on improving usage of

Example usage:

using CSRakowski.Parallel;

List<string> fileUrls = GetFileUrls();

var files = await ParallelAsync.ForEachAsync(fileUrls, (url) => {
    return DownloadFileAsync(url);
}, maxBatchSize: 8, allowOutOfOrderProcessing: true);

As of version 1.1 a fluent syntax is also available:

using CSRakowski.Parallel.Extensions;

List<string> fileUrls = GetFileUrls();

var files = await fileUrls
                    .AsParallelAsync()
                    .WithMaxDegreeOfParallelism(8)
                    .WithOutOfOrderProcessing(false)
                    .ForEachAsync((url) => {
                        return DownloadFileAsync(url);
                    });

In version 1.6, support for Async Streams has been added. This allows you to chain together multiple invocations by passing along an IAsyncEnumerable<T>, sort of like a pipeline:

using CSRakowski.Parallel;

List<string> fileUrls = GetFileUrls();

var fileDataStream = ParallelAsync.ForEachAsyncStream(fileUrls, (url) => {
    return DownloadFileAsync(url);
}, maxBatchSize: 4, allowOutOfOrderProcessing: true);

var resultStream = ParallelAsync.ForEachAsyncStream(fileDataStream, (fileData) => {
    return ParseFileAsync(fileData);
}, maxBatchSize: 4, allowOutOfOrderProcessing: true);

await foreach (var result in resultStream)
{
    HandleResult(result);
}

• Updated TargetFrameworks to remove old unsupported ones.

• First attempt at enabling SourceLink.

• Updated to latest CSRakowski.AsyncStreamsPreparations, which uses Microsoft.Bcl.AsyncInterfaces (correctly...).

• Updated to latest CSRakowski.AsyncStreamsPreparations, which uses Microsoft.Bcl.AsyncInterfaces.

• Added support for Async Streams, so you produce an IAsyncEnumerable<T>.

• Added .NET 6.0 TargetFramework

• Fixed dependency misconfiguration on net50

• Updated target frameworks

• Updated target frameworks

• Updated dependencies

• Added gist support for IAsyncEnumberable<T>

• Added the RunId to the BatchStart and BatchStop events

• Reduced overhead in code paths where the input collection is a T[], maxBatchSize is greater than 1 and allowOutOfOrder is false

• Changed assembly signing key
• Further changes to internal implementation details
• Performance improvements when the input collection is a T[] or IList<T> and maxBatchSize is set to 1
• Performance improvements in the allowOutOfOrder code paths.

• Marked the T on the IParallelAsyncEnumerable as covariant
• Changes to internal implementation details

• Added an EventSource to expose some diagnostic information.
• Changed minimum supported NetStandard from 1.0 to 1.1 (Because of the EventSource).

• Added support for IReadOnlyCollection<T> to the ListHelper.
• Added more XmlDoc to methods and classes.

• Renamed class to ParallelAsync to prevent naming conflicts with the System.Threading.Tasks.Parallel.
• Renamed namespace to CSRakowski.Parallel to prevent ambiguous name conflicts between the class and the namespace.
• Added new extension methods to allow for fluent sytax usage.

• Enabled Strong Naming.

• Initial release.