Warnings

Thread-local data

Libraries that use thread-local data and were not designed with
coroutines in mind may not be safe to use from multiple coroutines at
the same time.

For example, having several coroutines executing JavaScript and allowing
them to yield during script evaluation is not a good idea. At least not 
with JavaScriptCore.


Microsoft Windows

Using a heap based stack is not supported on Windows. The exception 
handler and some functions like OutputDebugString that use SEH will
notice that the stack is not where it should be and terminate the 
application.

When using coroutine you need to either avoid using anything SEH 
related from coroutines or implement a backend using Microsoft's Fiber
API.