String getIsolateID(Isolate isolate)

Returns a String token representing the ID of isolate.

Returns null if the running Dart environment does not support the service protocol.

Source 

static String getIsolateID(Isolate isolate) {
  if (isolate is! Isolate) {
    throw new ArgumentError.value(isolate, 'isolate', 'Must be an Isolate');
  }
  return _getIsolateIDFromSendPort(isolate.controlPort);
}