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dart中的isolate已经困扰我好几天了，主要项目需要，比如对数据库的处理，都放到一个单独的子isolate（子线程）中，优势在于，当数据库足够大时，对数据库的处理可能较为耗时，这时，只用dart的主isolate，可能会对其他逻辑的处理，造成阻塞。可能有人说，await、async不就可以异步实现吗，异步操作和子线程操作还是有很大区别的。这篇可以用作了解学习

最开始接触isolate时，主子isolate发送接收port，很容易绕晕，不过，结合一些网上资料，加上这个简单的demo，有助于理解，希望能帮到一些和我一样，因刚接触isolate而头疼的人。至少让我豁然开朗了，也看到了自己思维的局限性，不够扩散开来。

代码贴出如下，由于没用到什么插件，所以，不会对使用插件版本过度依赖，亲测，可本机直接$ dart run运行，另外，这只是个demo，不涉及任何项目内容的东西，但你看明白了，应用起来会很迅速，特此记录。

import 'dart:isolate';// 子 isolate 要执行的函数
void childIsolate(SendPort sendPort) async {// 创建一个 ReceivePort 来接收主 isolate 发送的数据ReceivePort receivePort = ReceivePort();// 将 ReceivePort 的 SendPort 发送给主 isolatesendPort.send(receivePort.sendPort);await for (var message in receivePort) {if (message is List && message.length > 3 && message[0] == 'insert') {print("childIsolate cur received: $message");SendPort responseSendPort = message[3];String table = message[1];String row = message[2];String ret = await DBUtils().insert(table, row);responseSendPort.send(ret);} else {print(": $message");}}
}class IsolateService {static Isolate? _isolate;static SendPort? _childSendPort;static final ReceivePort _receivePort = ReceivePort();static Future<void> init() async {_isolate = await Isolate.spawn(childIsolate, _receivePort.sendPort);await for (var message in _receivePort) {if (message is SendPort) {_childSendPort = message;break;}}}static Future<dynamic> sendAndReceive(dynamic message) async {if (_childSendPort == null) {throw Exception('childIsolate is not initialized. Call init() first.');}final responseReceivePort = ReceivePort();// 作为当前主调子一次的返回，一次处理完成后，需要close，下次再调时，再创建_childSendPort!.send([...message, responseReceivePort.sendPort]);try {final response = await responseReceivePort.first;print("mainIsolate has get the response fron childIsolate: $response");responseReceivePort.close();return response;} catch (e) {print('Error receiving response: $e');return null;}}static void dispose() {_receivePort.close();_isolate?.kill(priority: Isolate.immediate);}
}class DBUtils {Future<String> insert(String table, String row) async {// 模拟耗时任务for (int i = 0; i < 10; i++) {for (int j = 0; j < 100; j++) {for (int k = 0; k < 100; k++) {}}}return "ret from insert";}
}void main() async {await IsolateService.init();// 第一个场景Future(() async {final response1 = await IsolateService.sendAndReceive(['insert', 'table1', 'row1']);print("Received response in first scenario: $response1");});// 第二个场景Future(() async {final response2 = await IsolateService.sendAndReceive(['insert', 'table2', 'row2']);print("Received response in second scenario: $response2");});// 模拟程序结束时释放资源await Future.delayed(Duration(seconds: 5));IsolateService.dispose();
}