private Path createPath(Path path, boolean checkWrite) throws IOException {
      Path file = new Path(localDirsPath[dirNumLastAccessed], path);

      if (checkWrite) {
        // check whether we are able to create a directory here. If the disk
        // happens to be RDONLY we will fail
        try {
          DiskChecker.checkDir(new File(file.getParent().toUri().getPath()));
        } catch (DiskErrorException d) {
          LOG.warn(StringUtils.stringifyException(d));
          return null;
        }
      }
      return file;
    }
    /**
     * This method gets called everytime before any read/write to make sure that any change to
     * localDirs is reflected immediately.
     */
    private synchronized void confChanged(Configuration conf) throws IOException {
      String newLocalDirs = conf.get(contextCfgItemName);
      if (!newLocalDirs.equals(savedLocalDirs)) {
        String[] localDirs = conf.getStrings(contextCfgItemName);
        localFS = FileSystem.getLocal(conf);
        int numDirs = localDirs.length;
        ArrayList<String> dirs = new ArrayList<String>(numDirs);
        ArrayList<DF> dfList = new ArrayList<DF>(numDirs);
        for (int i = 0; i < numDirs; i++) {
          try {
            // filter problematic directories
            Path tmpDir = new Path(localDirs[i]);
            if (localFS.mkdirs(tmpDir) || localFS.exists(tmpDir)) {
              try {
                DiskChecker.checkDir(new File(localDirs[i]));
                dirs.add(localDirs[i]);
                dfList.add(new DF(new File(localDirs[i]), 30000));
              } catch (DiskErrorException de) {
                LOG.warn(localDirs[i] + "is not writable\n" + StringUtils.stringifyException(de));
              }
            } else {
              LOG.warn("Failed to create " + localDirs[i]);
            }
          } catch (IOException ie) {
            LOG.warn(
                "Failed to create "
                    + localDirs[i]
                    + ": "
                    + ie.getMessage()
                    + "\n"
                    + StringUtils.stringifyException(ie));
          } // ignore
        }
        localDirsPath = new Path[dirs.size()];
        for (int i = 0; i < localDirsPath.length; i++) {
          localDirsPath[i] = new Path(dirs.get(i));
        }
        dirDF = dfList.toArray(new DF[dirs.size()]);
        savedLocalDirs = newLocalDirs;

        // randomize the first disk picked in the round-robin selection
        dirNumLastAccessed = dirIndexRandomizer.nextInt(dirs.size());
      }
    }