Hi,

With later versions of Episerver/Optimizely, we've been given a abstraction called AsyncBlockComponent. According to the documentation, the purpose is "Provides the base implementation for asynchronus block components". I think that it's existence leads the developer into thinking this is a way to write true async code. Async child actions (= blocks) was maybe not allowed in .NET Framework, but this is no longer the case in .NET Core... I think, at least.

But! On the other hand, true async code must use async all the way or task return types, but using Html.PropertyFor(...) to render a content area is neither of them.

Digging deeper, I can see that rendering a content area is done via the method below (see bottom of post). Execution of block components are wrapped in a GetAwaiter().GetResult() context, which is NOT async code. Rather, this leads to deadlocks and downtime. 

In our scenario, we have a product recommendations blocks that render user-unique recommendations fetched from a REST API.

I guess I have three questions - is my understanding correct, was everyone aware of this, and, how do you solve the problem?

  public static void RenderContentData(
    this IHtmlHelper html,
    IContentData contentData,
    bool isContentInContentArea,
    TemplateModel templateModel,
    IContentRenderer contentRenderer)
  {
    html.ViewContext.HttpContext.RequestServices.GetRequiredService<HtmlGenerator>().RenderContentDataAsync(contentData, html.ViewContext, isContentInContentArea, templateModel, (string) null, contentRenderer).GetAwaiter().GetResult();
  }