}
final File targetDir = new File(assetDir, "virtual/" + indexName);
final ConcurrentSkipListSet<File> old = new ConcurrentSkipListSet();
old.addAll(FTBFileUtils.listFiles(targetDir));
Benchmark.reset("threading");
Parallel.TaskHandler th = new Parallel.ForEach(index.objects.entrySet())
.withFixedThreads(2 * OSUtils.getNumCores())
//.configurePoolSize(2*2*OSUtils.getNumCores(), 10)