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Tag: async

33 posts · Page 1 of 4

2026-10-03 csharp dotnet async

How to wait for a ValueTask synchronously in a non-async method without allocating

Check IsCompleted first and read the result through GetAwaiter().GetResult(), which costs 0 bytes. Only fall back to blocking when the ValueTask is still pending, and do that with a cached event and UnsafeOnCompleted instead of AsTask(), which allocates 72 to 208 bytes per call. Measured on .NET 10 and .NET 11 RC1.

2026-09-16 errors dotnet dotnet-10

Fix: UIKitThreadAccessException from MediaPicker.PickPhotosAsync when selecting multiple photos in .NET MAUI iOS

Picking 2 or more photos on iOS throws UIKitThreadAccessException in MAUI 10.0.100 and 10.0.101. MAUI reads PHPickerResult.ItemProvider after an await, off the main thread. Pin 10.0.90, upgrade to 10.0.110, or use a PHPicker shim.

2026-09-14 dotnet-11 dotnet csharp

How to Create and Extract ZIP Files Asynchronously with the ZipArchive Async APIs in .NET 11

Use ZipFile.CreateFromDirectoryAsync, ExtractToDirectoryAsync, ZipArchive.CreateAsync and ZipArchiveEntry.OpenAsync without hidden synchronous I/O. Measured on .NET 11 RC 1 and .NET 10.0.12, including the .NET 10 bug that still blocks Kestrel.

2026-09-07 dotnet dotnet-11 csharp

How to find the async void handlers causing ANRs in a .NET MAUI Android app

Play Console tells you your ANR rate is over 0.47% and hands you a native stack full of libcoreclr.so frames. Here is how to get from that useless trace to the exact async void event handler that blocked the main thread, using a Looper printer, a SynchronizationContext wrapper that names the state machine, and dotnet-trace over dsrouter.

2026-09-01 comparison csharp csharp-14

Returning a Task directly vs async/await passthrough in a C# repository method: which should you use?

Eliding async/await in a repository passthrough saves about 6 ns and 72 bytes, and costs you a stack frame, try/catch semantics, and safe disposal. Keep return await unless the method is a pure passthrough on a measured hot path.

2026-08-05 errors csharp dotnet

Fix: AggregateException "One or more errors occurred" when awaiting Task.WhenAll in C#

await Task.WhenAll rethrows only one of the failures. Keep the WhenAll task in a variable and read its Exception.InnerExceptions to see every error instead of one.

2026-08-05 errors csharp csharp-14

Fix: CS1998 "This async method lacks 'await' operators and will run synchronously" in C#

CS1998 means an async method has no await, so it runs synchronously. Drop the async modifier and return Task.FromResult, or add the await you forgot.

2026-07-26 csharp dotnet dotnet-11

How to test time-dependent code with TimeProvider and FakeTimeProvider in .NET 11

Replace DateTime.UtcNow, Stopwatch, and Task.Delay with System.TimeProvider so tests can control the clock: DI registration, FakeTimeProvider.Advance and SetUtcNow, testing timeouts and PeriodicTimer-based BackgroundServices, plus the Advance-continuation and xUnit v2 gotchas.

2026-07-25 migration csharp dotnet

Migrate from blocking .Result/.Wait() calls to async all the way up in a legacy C# codebase

A staged playbook for removing sync-over-async from an existing .NET codebase: inventory with analyzers, measure ThreadPool starvation, convert one call chain at a time, and ratchet the count to zero on .NET 11.

2026-07-24 comparison csharp dotnet

.Result vs .Wait() vs GetAwaiter().GetResult() vs await in C#: which should you use?

await is the right answer almost every time. When you truly must block, GetAwaiter().GetResult() beats .Result and .Wait() because it throws the original exception. A decision matrix for .NET 11 and C# 14.