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Upcoming changes to the isolate API

Posted by Sigmund Cherem

We are actively working on improving the isolate APIs. If you have code that uses isolates today, some of our upcoming changes will likely break your code. Here are a few of the changes coming up:
  • We are moving the isolates code out of corelib into a standalone 'dart:isolate' library.
  • We are making any top-level static function a valid entrypoint for an isolate, so you'll no longer have to create a class to define an isolate's entrypoint.
  • We want to simplify other parts of the API too, like how to obtain a port after spawning an isolate.
  • Later on, we plan to support spawning an isolate given a URL to its code.
For example, this code written with today's API:

// soon to be deprecated!
class MyIsolate extends Isolate {
  MyIsolate() : super.heavy();

  main() {
    port.receive((msg, reply) => reply.send("re: $msg"));
  }
}

main() {
  MyIsolate myIsolate = new MyIsolate();
  myIsolate.spawn().then((SendPort sendPort) {
    sendPort.call("hi").receive((msg, _) => print(msg));
  });
}


could be written as follows:

// coming soon!
#import('dart:isolate', prefix: 'isolate');

isolateCode() {
  isolate.port.receive((msg, reply) => reply.send("re: $msg"));
}

main() {
  SendPort sendPort = isolate.spawnFunction(isolateCode);
  sendPort.call("hi").then(print);
}


There are many details still under debate, so watch news.dartlang.org for updates when these and future changes land in trunk.

Comments

  1. This change appears to break the promise that a heavy isolate will run inside a web worker. How does one force this such that sync APIs like for filesystem and such are guaranteed to be visible?

    ReplyDelete
  2. For dart-to-js compiled applications we want to make workers the default. If web workers are available, we'll try to spawn new isolates in a worker. We won't necessarily guarantee that each isolate has its own worker (e.g. when we eventually support creating a very large number of isolates).

    Soon we'll also add a different API to run an isolate in the DOM UI thread if it needs access to the DOM.

    -- Sigmund

    ReplyDelete

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