Function is_threaded

localtime.c:106–116

True if the current process might be multi-threaded, false if it is definitely single-threaded. If false, it will be false the next time it is called unless the caller creates a thread in the meantime. If true, it might become false the next time it is called if all other threads exit in the meantime. */

   If true, it might become false the next time it is called
   if all other threads exit in the meantime.  */
static bool
is_threaded(void)
{
#  if THREAD_PREFER_SINGLE && HAVE___ISTHREADED
  return !!__isthreaded;
#  elif THREAD_PREFER_SINGLE && HAVE_SYS_SINGLE_THREADED_H
  return !__libc_single_threaded;
#  else
  return true;
#  endif
}

#  if THREAD_RWLOCK
static pthread_rwlock_t locallock = PTHREAD_RWLOCK_INITIALIZER;