throttle_lock
mutex_lock(&data->throttle_lock);
mutex_unlock(&data->throttle_lock);
mutex_init(&data->throttle_lock);
mutex_lock(&data->throttle_lock);
mutex_unlock(&data->throttle_lock);
mutex_lock(&data->throttle_lock);
mutex_unlock(&data->throttle_lock);
struct mutex throttle_lock;
throttle_lock(&pool->throttle);
throttle_lock(&pool->throttle);