How to determine worker termination cause?

[diversario]

I create workers with this bit of code:

for (var i = 0; i < MAX_WORKERS; i++){
  arr[i] = new Worker(CURRENT_DIR + '/lib/workers/worker.js');

  arr[i].onmessage = function(msg, cb) { ... }
  }

  arr[i].onexit = function(code, syssignal){
    console.log("\033[1;32m#### WORKER TERMINATED, signal %s #####\033[0m", syssignal);
  };

}

My intention is to use long-lived workers and rotate through them (I'm using them for file upload handling). Is this the right approach?

Second, these workers terminate with signal null when server is under heavy load (not file uploads, but just GET /). Why would they do that and how can I figure out why they crash?