How to ensure a thread cannot be blocked by the GC?

[via Digitalmars-d-learn]

On Thursday, 4 December 2014 at 01:36:13 UTC, Ola Fosheim Grøstad 
wrote:
> So I suppose none of your threads are suspended unless you 
> suspend it with Thread on call_back entry? But why suspend a 
> @nogc thread?

What a mess of incorrect recollection and typos (it is late, 3AM 
:-P): I  meant to say that I suppose none of your threads are 
suspended unless you register it as a Thread before the call_back 
entry. But if you do it on the call_back entry point by 
registering a fake Thread object you must ensure that you are not 
already in a collection cycle before continuing…

Seems to me that there should either be better documentation of 
GC behaviour or some extra functionality for controlling GC 
interference with threads and Threads. I also find this 
confusing… There is a lot of policy making in D's runtime and 
standard library.