await using asynchronous disposable

Context: await using disposes an IAsyncDisposable object asynchronously, typically used with await foreach to dispose the enumerator asynchronously.

using System;
using System.Data.SqlClient;
using System.Threading.Tasks;

public class DatabaseService
{
    public async Task ProcessAsync()
    {
        await using var connection = new SqlConnection(connectionString);
        // connection is disposed asynchronously at the end of the scope
    }

    private string connectionString = "Server=.;Database=MyDb;Trusted_Connection=true;";
}

Implementing IAsyncDisposable

using System;
using System.Threading.Tasks;

public class AsyncResource : IAsyncDisposable
{
    public async ValueTask DisposeAsync()
    {
        await CleanupAsync();
    }

    private Task CleanupAsync() => Task.Delay(100);
}

Real-world usage example

Database connections: SqlConnection implements IAsyncDisposable. Using await using ensures asynchronous cleanup.

Example: IAsyncDisposable documentation

Related sections

• 9.4 Asynchronous streams
• 9.4.2 await foreach