final BlockingQueue<Task> failQ = grid.queue("grouperfish_fail");
// Here we could in theory create e.g. several run workers instead of just one for this host...
workers = new ImmutableList.Builder<Worker>()
.add(new Worker(failQ, prepQ, runQ, new FetchHandler(fs, indexes)))
.add(new Worker(failQ, runQ, putQ, new RunHandler(fs, transforms)))
.add(new Worker(failQ, putQ, cleanupQ, new PutHandler(grid, fs)))
.add(new Worker(failQ, cleanupQ, null, new CleanupHandler(fs)))
.build();