async / await deadlock而不使用Task.Result

Question

I have a web api that is using async/await all the way down:

public class SampleController : ApiController
{
    public async Task<IEnumerable<DocumentModel>> GetAll()
    {
        List<DocumentModel> modelItems = new List<DocumentModel>();

        var response = await SearchDocumentsAsync();
        var items = response.Results.ToList();
        foreach(var document in documents)
        {
            var model = new DocumentModel()
            {
                Id = document.Id,
                Name = document.Name
            };

            modelItems.Add(model);
        }

        return modelItems;
    }

    private Task<DocumentSearchResponse<Document>> SearchDocumentsAsync()
    {
        using (var searchClient = new SearchServiceClient(new SearchCredentials(searchServiceKey), searchServiceUri))
        using (var indexClient = searchClient.Indexes.GetClient(indexName))
        {
            var parameters = new SearchParameters()
            {
                IncludeTotalResultCount = true
            };

            // call the Azure Search service
            return indexClient.Documents.SearchAsync<Document>(search.Term, parameters);
        }
    }    
}

I am not using .Wait() or .Result anywhere in the call stack. Is it still possible for code like this to deadlock? When I debug this code I seem to be experiencing one but for the life of me I can't figure out why.

I have used Postman to send a couple of requests and sometimes the response never comes back. If I press the pause button in the debugger it will show a line in green that says "This is the next statement to execute when this thread returns from the current function." It is not consistent where the code will be when I press the pause button, but it seems that every other request will be blocked once one of them gets blocked.

Can the code above deadlock?

Answer 1

In SearchDocumentsAsync , you're immediately returning the task from SearchAsync .

You should be awaiting this task to ensure indexClient and searchClient aren't disposed before the operation is complete. These being disposed may be what is introducing a deadlock.