dart2js not using web worker for isolate

[sethladd]

This code doesn't seem to be using a web worker. I tested by setting breakpoint on line of "new Worker" and it's never hit.

import('dart:html');

import('dart:isolate');

myIsolate() {
  port.receive((msg, reply) {
    print("isolate received message");
    var s = new StringBuffer();
    // simulate heavy work
    for (var i = 0; i < 600000; i++) {
      s.add("$i");
    }
    reply.send("I received: ${s.toString()}");
  });
}

main() {
  var sendPort = spawnFunction(myIsolate);
  
  query('#myButton').on.click.add((Event e) {
    print("just clicked");
      sendPort.call("Hello from main").then((reply) {
        print("done with message size ${reply.length}");
      });
    print("sent request to isolate");
  });
  
}

I've attached the compiled JS output.

Should isolates use web workers when compiled to JavaScript ?

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Attachment:
isolatesinweb.dart.js (201.12 KB)

[sethladd]

Digging in, it looks like "$._globalState().get$useWorkers()" is returning undefined. (line 4242) How do we set $supportsWorkers ?

[DartBot]

This comment was originally written by ngeoffray@google.com

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When I did the original port of the frog code for isolates to dart2js, I think I only made sure we could run isolates. So web workers may not work out of the box and some new magic JS glue might be needed.

[sigmundch]

That's right - the implementation in dart2js is not working correctly exactly for that reason. The library implementation simulates isolates in the UI thread as a fallback.

Thanks for filing the bug. I thought I already had filed a bug about this a while back, but I wasn't able to find it.

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cc @floitschG.
cc @kasperl.

[kasperl]

Assigning to Florian.

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Set owner to @floitschG.
Added Accepted label.

[kasperl]

Added this to the Later milestone.

[sigmundch]

Marked this as blocking #2599.

[sigmundch]

Added Library-Isolates label.

[DartBot]

This comment was originally written by jjinux...@google.com

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Whenever this is ready, I want to take a stab at porting (http://www.html5rocks.com/en/tutorials/workers/basics/) to Dart.

[kasperl]

Removed this from the Later milestone.

[kasperl]

Added this to the M2 milestone.

[floitschG]

Removed the owner.
Added Triaged label.

[peter-ahe-google]

Set owner to ngeoffray@google.com.

[DartBot]

This comment was originally written by trapped.into...@gmail.com

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Evaluating Dart and looks awesome. This is an important feature for my use case. Is there a workaround I can use with current code base? Or even some "magic glue" as mentioned in one of the comments?

[DartBot]

This comment was originally written by ngeoffray@google.com

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Thanks for the feedback. I don't think there is any easy workaround for supporting web workers, other than implementing it :) But getting support back for web workers in isolates is definitely in our radar.

[DartBot]

This comment was originally written by trapped.into...@gmail.com

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Thanks for getting back.

Isolates are great, of course I understand with the design limitations on Workers, its not trivial to translate them. I did read somewhere Frog supported Isolates to Workers? or it was not so?

I can just work with plain Workers too. It was my plan before my eyes lit up seeing Isolates. What about Worker from dart:html? Is that class translated correctly?

[DartBot]

This comment was originally written by ngeoffray@google.com

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Yes, Workers in the html library are translated correctly, so you could start playing with them until we use them for isolates.

[kasperl]

Postponing until M3. CL out for review: https://codereview.chromium.org/11553024/.

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Removed this from the M2 milestone.
Added this to the M3 milestone.
Added Started label.

[kwalrath]

It looks like this was committed December 14. So maybe it works now?

[kasperl]

Nope - still doesn't work. The commit was reverted.