Asynchronous operation does not work even though I wrote it with async / await - C#

Question

it's been a while that I try to write asynchronous code in C#, I did it and was sure it is asynchronous, recently I read I checked with postman the time that the function takes to finish when it's Asynchronous and when it's synchronous, and it seems like it takes the SAME time exactly, what I did wrong in my code?

Here is my code:

    [HttpGet]
    [Route("customerslist")]
    public async Task<IHttpActionResult> getData()
    {
        string url1 = @"https://jsonplaceholder.typicode.com/photos";
        string url2 = @"https://jsonplaceholder.typicode.com/comments";
        string url3 = @"https://jsonplaceholder.typicode.com/todos";

        Task<string> firstTask = myHttpCall(url1);
        Task<string> secondTask = myHttpCall(url2);
        Task<string> thirdTask = myHttpCall(url3);

        await Task.WhenAll(firstTask, secondTask, thirdTask);

        var result = firstTask.Result + secondTask.Result + thirdTask.Result;
        return Ok(result);
    }

    private async Task<string> myHttpCall(string path)
    {
        string html = string.Empty;
        string url = path;

        // Simple http call to another URL to receive JSON lists.
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.AutomaticDecompression = DecompressionMethods.GZip;

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (Stream stream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(stream))
        {
            html = reader.ReadToEnd();
        }

        return html;
    }

I make HTTP request to another URL to get their JSON lists, anyone can help me please? I will be happy if anyone can tell me how to write it properly.

Why should the execution time be any different for sync and async? the amount of code executed is the same especially if you are not running any other code. — jdweng, Aug 12 '17 at 11:23
There's also nothing async about the `myHttpCall` method, you're not awaiting anything inside it. — DavidG, Aug 12 '17 at 11:24
Indeed, you should be getting a warning about an async method with no await... — Jon Skeet, Aug 12 '17 at 11:30
@jdweng: If `myHttpCall` where *really* asynchronous, the three requests would be made in parallel, leading to shorter overall time. — Jon Skeet, Aug 12 '17 at 11:31
Please read your compiler warnings. The C# compiler says: "This async method lacks 'await' operators and will run synchronously." — Stephen Cleary, Aug 12 '17 at 13:19
it depends on the bandwidth of the channel how much improvement you would have and the response times of the servers. — jdweng, Aug 12 '17 at 15:08

score 2 · Answer 1 · answered Aug 12 '17 at 11:26

2

Your HTTP calls are synchronous. Use HttpClient in your myHttpCall method more or less like this:

private async Task<string> myHttpCall(string path)
{
    using(HttpClient client = new HttpClient())
    {
           HttpResponseMessage response = await client.GetAsync(path);
           return await response.Content.ReadAsStringAsync();
    }
}

EDIT: To add automatic decompression pass following object to HttpClient constructor:

HttpClientHandler handler = new HttpClientHandler()
{
    AutomaticDecompression = DecompressionMethods.GZip
};

answered Aug 12 '17 at 11:26

Kedrzu

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3

While it is definitely non-obvious, `HttpClient` is meant to be re-used, not created and disposed every time. We should try to get out of the habit of recommending this pattern with `HttpClient`. – Crowcoder Aug 12 '17 at 11:41
Interesting, I didn't know about it. More details [here](https://stackoverflow.com/questions/15705092/do-httpclient-and-httpclienthandler-have-to-be-disposed) – Kedrzu Aug 12 '17 at 11:52

Asynchronous operation does not work even though I wrote it with async / await - C#

1 Answers1