d = xbt_dynar_new_sync(sizeof(int), NULL);
pusher = xbt_thread_create("pusher", pusher_f, d, 0 /*not joinable */ );
poper = xbt_thread_create("poper", poper_f, d, 0 /*not joinable */ );
d = xbt_dynar_new_sync(sizeof(int), NULL);
pusher = xbt_thread_create("pusher", pusher_f, d, 0 /*not joinable */ );
poper = xbt_thread_create("poper", poper_f, d, 0 /*not joinable */ );