Function walk_dir_parallel 

fn walk_dir_parallel(
    dir: &Path,
    depth: u32,
    visited: &Arc<DashSet<PathBuf>>,
    tx: &SyncSender<ClassifiedBatch>,
    audio_found: &Arc<AtomicUsize>,
    daw_found: &Arc<AtomicUsize>,
    preset_found: &Arc<AtomicUsize>,
    pdf_found: &Arc<AtomicUsize>,
    batch_size: usize,
    stop: &Arc<AtomicBool>,
    spec: &Arc<UnifiedSpec>,
    active_dirs: &[Arc<Mutex<Vec<String>>>],
    tcc_denied: &Arc<DashSet<PathBuf>>,
    incremental: Option<Arc<IncrementalDirState>>,
)