the following code snipped from libjit/jit/jit-thread.c contains a race condition. If a thread entering the if-branch is interrupted by scheduler in line 74, other thread will assume init_win32_thread() has already been called.
     71         static LONG volatile once_control = 0;
     72         if(!InterlockedExchange((PLONG)&once_control, 1))
     73         {
     74                 init_win32_thread();
     75         }

Attached you find a fix for this bug.