I’m trying to write a method that reads each page of a pdf, but since it takes a significant amount of time to read each page through the api and I’m looking at pdfs hundreds of pages long, I want to queue the reading of each page asynchronously and then return the results when they’re ready, so multiple pages are being read at once.

I use Task.Run to “queue” the task, and I expect to see the Debug log print the pages out of order, but they only execute in order, so I think they are being run synchronously. Any ideas?

var tasks = new List<Task>();
foreach (Page page in _pdfDoc.GetPages()) {
    var task = Task.Run(() => {
        //tried adding await Task.Yield() here, doesn't work
        Debug.WriteLine("searching page " + page.Number);
        if (page.Text.Contains(query)) {
            pagesWithQuery.Add(page.Number);
        }
        howManySearched += 1;
        Dispatcher.UIThread.InvokeAsync(() => {
            searchProgress.Value = howManySearched;
        });
        return Task.CompletedTask;
    });
    tasks.Add(task);
    // await task; <== does nothing??
}