pthread_mutex_lock(&c->iolock);
_xcb_out_write_block(c, parts, count);
ret = _xcb_out_flush(c);
pthread_mutex_unlock(&c->iolock);
pthread_mutex_lock(&c->iolock);
_xcb_out_write_block(c, parts, count);
ret = _xcb_out_flush(c);
pthread_mutex_unlock(&c->iolock);