code: public void stopSyncForMount(long mountId) throws InvalidPathException, IOException {
      LOG.debug("Stop sync for mount id {}", mountId);
      if (mFilterMap.containsKey(mountId)) {
        List<Pair<AlluxioURI, MountTable.Resolution>> toBeDeleted = new ArrayList<>();
        for (AlluxioURI uri : mFilterMap.get(mountId)) {
          MountTable.Resolution resolution = resolveSyncPoint(uri);
          if (resolution != null) {
            toBeDeleted.add(new Pair<>(uri, resolution));
          }
        }
        // Calling stopSyncInternal outside of the traversal of mFilterMap.get(mountId) to avoid
        // ConcurrentModificationException
        for (Pair<AlluxioURI, MountTable.Resolution> deleteInfo : toBeDeleted) {
          stopSyncInternal(deleteInfo.getFirst(), deleteInfo.getSecond());
        }
      }
    }
docs: stop active sync on a mount id.
  
  @param mountId mountId to stop active sync