问题
Is there a possibility to use thread static like variables within a single request? The current code uses a thread static variable for logging purposes and now we want to use async controller methods (with async and await pattern) which results in problems because the variable is null when a new thread is opened.
回答1:
await can cause thread jumps, so thread static variables will naturally cause problems.
To work around this, you can either use AsyncLocal<T> (available in .NET 4.6), or (if you must) HttpContext.Current.Items. Of those two, I would definitely recommend AsyncLocal<T> over Items, if it's available on your platform.
来源：https://stackoverflow.com/questions/42507054/threadstatic-in-asynchronous-asp-net-web-api