code: function closeAllWorkers() {
          Object.keys(cluster.workers).forEach(id => {
  
              // Get a handle on the worker process
              const worker = cluster.workers[id];
  
              // Check this worker isn't already done
              if (worker.state === "disconnected") {
                  return;
              }
  
              // Tell the worker to shutdown
              worker.send("pluribus-shutdown");
              worker.disconnect();
  
              // If the worker is too slow, shut it down anyway
              const timeout = setTimeout(_ => {
                  logger("Forcing", worker.process.pid, "to shutdown");
                  worker.kill("SIGKILL");
              }, options.waitTimeout);
  
              // If the worker shuts down okay, cancel the forced shutdown
              worker.on("exit", function () {
                  logger("Worker", worker.process.pid, "exited");
                  clearTimeout(timeout);
              });
          });
      }
docs: closeAllWorkers()
  Tells all the worker processes to finish what they are doing and abort.
  If they're too slow about it, then we kill them anyway.