public void init() throws IOException {
    if (localDir.exists()) {
      // TODO: We don't want some random jars of unknown provenance sitting around. Or do we care?
      //       Ideally, we should try to reuse jars and verify using some checksum.
      FileUtils.deleteDirectory(localDir);
    }
    this.resourceDownloader = new ResourceDownloader(conf, localDir.getAbsolutePath());
    workThread.start();
  }
This class localizes and manages jars for the functions allowed inside LLAP.
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/FunctionLocalizer.java