Illegal argument in isolate message : (function types are not supported yet)

[wustrong]

This tracker is for issues related to:

• Dart VM

• Dart SDK Version (dart --version)
  Dart SDK version: 2.10.3 (stable) (Tue Oct 27 14:44:30 2020 +0100) on "linux_x64"

I tried to spawn a new isolate，but failed. I do not know why and how to figure it out . the error response like this：

startup tcp isolates failed, error: Invalid argument(s): Illegal argument in isolate message : (function types are not supported yet), stacktrace: #0 spawnFunction (dart:_internal-patch/internal_patch.dart:184:54)
#1 Isolate.spawn (dart:isolate-patch/isolate_patch.dart:380:7)
#2 IsolateServerTransport._spawn (package:trpc_dart/src/transport/isolate_server_transport.dart:38:35)
#3 IsolateServerTransport._spawnTCP (package:trpc_dart/src/transport/isolate_server_transport.dart:45:12)
#4 IsolateServerTransport.listenAndServeStream (package:trpc_dart/src/transport/isolate_server_transport.dart:60:39)
#5 DefaultServerTransport.listenAndServe (package:trpc_dart/src/transport/server_transport.dart:56:15)
#6 ServiceImpl.serve (package:trpc_dart/src/server/service.dart:138:28)
#7 Server.serve (package:trpc_dart/src/server/server.dart:56:19)
#8 main (file:///home/strongwu/code/trpc/trpc-dart/example/helloworld/bin/server.dart:23:18)
#9 _startIsolate. (dart:isolate-patch/isolate_patch.dart:299:32)
#10 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:168:12)

here is my code:

top-level or static method

void workerEntryPoint(IsolateWorker worker) {
  worker.start();
}

spawn

    final worker = IsolateWorker(ctx, lsOpts, id, receivePort.sendPort, networkType);
    final isolate = await Isolate.spawn(workerEntryPoint, worker, paused: true, debugName: id);

entrypoint message

class IsolateWorker {
  SendPort supervisingSendPort;

  ReceivePort supervisingReceivePort;

  // simple class
  Context ctx;

  // simple class
  ListenServeOptions lsOpts;

  String id;

  int networkType;

  Stream<Socket> _listener;

  RawDatagramSocket _udpConn;

  IsolateWorker(this.ctx, this.lsOpts, this.id, this.supervisingSendPort, this.networkType);

  Future start() async {
    supervisingReceivePort = ReceivePort();
    supervisingReceivePort.listen(listener);
    logger.info('IsolateServer($id) listening, sending port');
    supervisingSendPort.send(supervisingReceivePort.sendPort);
   ....
  }
}

[a-siva]

We do not support sending of ReceivePort across isolates. In the example above when the isolate is spawned the 'worker' object is sent across. This object is of type IsolateWorker which has a ReceivePort field 'supervisingReceivePort'.
Maybe you could re structure your code to not have this field in the IsolateWorker class.

[wustrong]

We do not support sending of ReceivePort across isolates. In the example above when the isolate is spawned the 'worker' object is sent across. This object is of type IsolateWorker which has a ReceivePort field 'supervisingReceivePort'.
Maybe you could re structure your code to not have this field in the IsolateWorker class.

@a-siva I dont send ReceivePort when spawn the worker, that supervisingReceivePort is new in start() method.

[wustrong]

The reason is that the any field of object in message of entrypoint can not contain a Function type, as show in error.

feature support function type will be add new SDK version?

@a-siva

[mkustermann]

@wustrong I suspect that either Context or ListenServeOptions will transitively have a function type or a closure (tracked at #40370) in it.

It is very easy to reproduce such cases:

import 'dart:isolate';

Type getType<T>() => T;
main() async => await Isolate.spawn(entrypoint, getType<void Function()>());
void entrypoint(dynamic x) {}

which results in

Invalid argument(s): Illegal argument in isolate message : (object is a FunctionType)

or

import 'dart:isolate';

Function getClosure() => () {};
main() async => await Isolate.spawn(entrypoint, getClosure());
void entrypoint(dynamic x) {}

which results in

Invalid argument(s): Illegal argument in isolate message : (object is a closure - Function '<anonymous closure>': static.)

Both of these issues we intend to fix with lightweight isolates (see #36097) which is nearing it's completion - so stay tuned :-)

[mkustermann]

Closing this issue, merge into the more general #46623.