static double TimeFindPrimes( int nthread ) {
Primes.clear();
tbb::task_scheduler_init init(nthread);
tbb::tick_count t0 = tbb::tick_count::now();
tbb::parallel_for( tbb::blocked_range<Number>(0,1000000,500), FindPrimes() );
tbb::tick_count t1 = tbb::tick_count::now();
return (t1-t0).seconds();
}
bool clear_keyframes(std_srvs::Empty::Request &req,
std_srvs::Empty::Response &res) {
boost::mutex::scoped_lock lock(closest_keyframe_update_mutex);
keyframes.clear();
return true;
}