Why does OSThread exist?

[Thomas Stüfe]

Hi,

does anybody know what the point is of a separate OSThread companion class
to Thread? I understand that there is OS-specific information one wants to
factor out on a per-platform base, but why two physically separate
structures? AFAICS they never exist separately (an OSThread makes no sense
without a Thread, and vice versa). We pay unnecessarily for two
allocations, C-heap fragmentation, and for one additional dereferencing hop
when accessing OSThread.

Thanks, Thomas