Brtdku

We are downloading a lot of data from a webservice. This is done in discrete calls, with the number of rows in the reply (json) vary from a few thousand to arround half a million. This will take from a couple of seconds to about 90 seconds. We do about 200 calls in one night, some night we do perhaps 500 calls.

After receiving the data I consume the JSON, and bulk insert into SQL Server. This is about 10 times faster than the webrequest.

I've tried to make the webrequests parallel by adding the calls to a task list, and then using Whenany to wait for a task to finish

However when I look at the task list efter WhenAny completes, I have no tasks running.

I have my queries in the list "queries", and I try to add the requests t the task list "Replies"

List<Task<HttpResponseMessage>> Replies = new List<Task<HttpResponseMessage>>();

while (queries.Count > 0 || Replies.Count > 0)

{

    while (Replies.Count < 10 && queries.Count > 0)

    {

        string json = queries.First();

        queries.RemoveAt(0);

        HttpRequestMessage rMessage = new HttpRequestMessage(HttpMethod.Post, "");

        rMessage.Headers.Add("Authorization", Token);

        rMessage.Content = new StringContent(json, Encoding.UTF8, "application/json");

        Replies.Add(client.SendAsync(rMessage, HttpCompletionOption.ResponseHeadersRead));

    }



    var finished = await Task.WhenAny(Replies);

    int succeeded = Replies.Where(a => a.Status == TaskStatus.RanToCompletion).Count();

    int running = Replies.Where(a => a.Status == TaskStatus.Running).Count();

    int waitingact = Replies.Where(a => a.Status == TaskStatus.WaitingForActivation).Count();

    int waitingrun = Replies.Where(a => a.Status == TaskStatus.WaitingToRun).Count();

    Console.WriteLine("Got Reply -   {0} succeeded,{1} running,{2} wact,{3} wrun", succeeded, running, waitingact, waitingrun);

    Replies.Remove(finished);

}

I would expect there to be at least one task running after WhenAny completes, but there is just on with status "RanToCompletion", and all the other tasks have the status "WaitingForActivation"

I have tried to loo the list and call "Start" on each task, but that is not possible.

All of this is included in an async task, that is called from Main in a console app, it is run as

RunBlock().GetAwaiter().OnCompleted(() => { Console.WriteLine("Done"); });

How do I make the tasks run in parallel?

I would expect there to be at least one task running after WhenAny
completes, but there is just on with status "RanToCompletion", and all
the other tasks have the status "WaitingForActivation"

You're most likely confusing Delegate Tasks with Promise Tasks.

Delegate tasks (thread pool tasks) are created with statuses either Created or WaitForActivation and then through WaitingToRun they changing their status to Running...

Promise tasks (that are generated by async/await) don't have status Running instead from WaitForActivation they change their status directly to RanToCompletion/Faulted/Canceled.

The Tasks are most likely running they just have different status.

You could find this explained very well in an amazing article by Stephen Cleary.