public ProgressLoggers addQueueStats(WorkQueue<?> queue) {
    loggers.add(new WorkerPipelineLogger(() -> " -> " + padLeft("(" +
      format.numeric(queue.getPending(), false) + "/" +
      format.numeric(queue.getCapacity(), false) + ")", 9)
    ));
    return this;
  }
Adds the current number of items in a queue and the queue's size to the output.
planetiler-core/src/main/java/com/onthegomap/planetiler/stats/ProgressLoggers.java