Task, async and await, ConfigureAwait, cancellation tokens, Parallel, locks and thread safety in C#.
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- What is an async method in C#?
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A method that can pause execution and resume later without blocking threads, marked with the async keyword.- What does the await keyword do?
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Pauses execution of an async method until the awaited Task completes, then resumes automatically.- What is the difference between Task and Task<T>?
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Task represents an operation with no return value. Task<T> represents an operation that returns a value of type T.- What does ConfigureAwait(false) do?
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Prevents the continuation from running on the original synchronization context after the await.- When should you use ConfigureAwait(false)?
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In library code where you do not need to return to the UI or original synchronization context.- What is a cancellation token in C#?
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A mechanism to signal that an operation should stop, preventing unwanted work from running.- What class provides cancellation tokens?
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CancellationTokenSource creates tokens. CancellationToken is the parameter type passed to operations.- How do you check if cancellation was requested?
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Call ThrowIfCancellationRequested() to throw an exception, or check the IsCancellationRequested property.- What does Parallel.For do?
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Executes loop iterations concurrently across multiple threads instead of sequentially.- What is the difference between Parallel.For and a regular for loop?
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Parallel.For may execute iterations out of order and concurrently. A regular for loop is strictly sequential.- What is PLINQ?
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Parallel LINQ. Adding .AsParallel() to a LINQ query makes it execute across multiple cores.- What is the lock keyword used for?
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Acquires an exclusive lock on an object to ensure only one thread accesses code at a time.- What happens if a thread tries to acquire a lock that is already held?
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The thread blocks until the lock is released by the thread holding it.- What is Monitor.Enter and Monitor.Exit?
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Low-level synchronization methods: Monitor.Enter acquires a lock on an object, Monitor.Exit releases it.- What is a Mutex in C#?
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A kernel-level synchronization primitive that ensures only one thread can access a resource at a time. Can be named and cross-process.
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