Creating new isolate in dart and communicate with it

main.dart

/// Creating new isolate and communicate with it

import 'dart:convert';
import 'dart:isolate';

import 'package:stream_transform/stream_transform.dart';

void main() => Future<void>(() async {
      final receivePort = ReceivePort();
      final stream = receivePort.asBroadcastStream();
      final isolate = await Isolate.spawn<SendPort>(jsonParser, receivePort.sendPort);
      final sendPort = await stream.whereType<SendPort>().first;
      final jsonStream = stream.whereType<ParseResult>();
      Future<Object> parse(String json) {
        sendPort.send(json);
        return jsonStream.firstWhere((e) => e.source == json).then<Object>((e) => e.result);
      }

      await Stream<Object>.fromFutures(<Future<Object>>[
        parse('{"key":"value"}'),
        parse('[1, 2, 3]'),
        parse('{"list": ["a", "b", "c"]}'),
      ]).forEach(print);

      receivePort.close();
      isolate.kill();
    });

void jsonParser(SendPort sendPort) {
  final receivePort = ReceivePort();
  sendPort.send(receivePort.sendPort);
  receivePort.where((Object? e) => e is String).cast<String>().forEach((json) {
    sendPort.send(ParseResult(json, jsonDecode(json) as Object));
  });
}

class ParseResult {
  const ParseResult(this.source, this.result);
  final String source;
  final Object /* Map<String, Object?> or List<Object> */ result;
}