我会使用其他分离菌株的onExit处理程序来报告它们何时死亡，然后在主分离菌株中侦听。
所以：

var exitPort = RawReceivePort();
var liveIsolates = 0;
// Don't close port while still creating new isolates.
var isInitializing = true;
exitPort.handler = (_) {
  if (--liveIsolates == 0 && !isInitializing) exitPort.close();
};

try {
  for (var i = 0; i < x; i++) {
    liveIsolates++;
    ... Isolate.spawn(...., onExit: exitPort.sendPort) ...
  }
} finally {
  isInitializing = false;
  if (liveIsolates == 0) {
    // All isolate terminated already (or `x` was zero).
    exitPort.close();
  }
}

这将在每个派生的isolate退出时向exitPort发送（null）消息。当它们全部完成时，主isolate关闭其最后一个接收端口，并且也可以关闭。

您应该创建一个ReceivePort，然后将此示例作为参数发送到您的Isolate示例（根据所需的细节量，为每个Isolate创建一个ReceivePort或重复使用相同的ReceivePort）。通过这样做，您可以将数据发送回主隔离菌株，并且主隔离菌株不会停止，因为它有一个打开的ReceivePort，可以防止隔离菌株停止。
例如，您可以设置它，以便HTTP服务器可以要求关闭整个服务器。或者，您可以只保持ReceivePort示例打开，这将防止主隔离停止，而无需忙碌着等待（在这种情况下，您不需要将SendPort示例发送到隔离中。Dart不会跟踪ReceivePort何时应该关闭，所以你必须手动关闭它，当你认为它已经完成）。
示例：

import 'dart:async';
import 'dart:isolate';

void main() {
  ReceivePort receivePort = ReceivePort();
  receivePort.listen((message) {
    print('Got: $message');

    if (message == 'Goodbye') {
      print('Close ReceivePort and therefore also the program since '
          'nothing else are running that could trigger an event.');
      receivePort.close();
    }
  });

  Isolate.spawn(myIsolate, receivePort.sendPort);
}

void myIsolate(SendPort msg) {
  print('Running inside isolate. Wait 5 seconds before sending message back');
  Timer(const Duration(seconds: 5), () => msg.send('Goodbye'));
}