Is it possible to use the await operation inside a critical section protected by a lock?

You cannot use the await operation inside a critical section protected by a standard lock (for example, lock in C#). The reason is that await pauses the execution of the method and returns control to the calling code, while the lock remains held. This can lead to deadlocks, as other threads will not be able to access the locked resource.

If you need to use asynchronous code within a critical section, it is better to use asynchronous synchronization primitives, such as SemaphoreSlim with the WaitAsync method:

private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1,1);

public async Task SomeMethodAsync()
{
    await _semaphore.WaitAsync();
    try
    {
        await SomeAsyncOperation();
    }
    finally
    {
        _semaphore.Release();
    }
}

This way, asynchronous code does not block the thread and manages access to the resource correctly.