This is great! What feels like ages ago I attempted to include the Julia runtime in a C++ application and it was quite difficult, as only one thread was allowed to call the runtime (not just one thread at a time, one particular thread; if it was called by any other thread than that one particular thread it or the GC would get corrupted somehow and crash).
Yes that is precisely what was fixed, essentially the thread local storage that Julia was expecting were not setup and thus calling the runtime from a foreign thread would cause a crash.
This now enables to dynamically add and remove threads.
