Unexpected behavior when receiving multiple objects in GH

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1

Hi all,

We have created a query system in GH that lets us query objects in multiple streams and returns a list of objects’ URLs. We then need to receive them in GH but we cannot use any of the Recieve components.

  • The Async Receiver just receives the first objects when provided a list of URLs as the input. Having a glance at the source code, I guess this behavior is by design.

  • The Sync Receiver though has unexpected behavior. if provided a List or a DataTree, the component loops over the input but downloads the first object every time.

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In case of the Sync Receiver, this is presumably not the intended behavior, but one thing that is puzzling me a bit is if it was intended to behave like the Async Receiver and receive one object only, or if it was supposed to download a list of objects. The component is TaskCapable and the input has GH_ParamAccess.item which makes it loop over the input; but in the SolveInstance method, there is this line that reads the input only once.

    protected override void SolveInstance(IGH_DataAccess DA)
    {
      if (RunCount == 1)
      {
        ParseInput(DA);
        if (InputType == "Invalid") return;
      }

      if (InPreSolve)
      {
        ...

Also, since the variables are mostly class variables, I am not sure about the thread safety of the code. Is it something about the SynchronizationContext that I am missing?

1 Like
2

Hey @Ardeshir_Talaei!

Hmm… the sync component was developed by @Stam, so maybe he can give more insight on this, but it sounds like its definitely a bug. As far as I’m aware, the Sync nodes should be able to receive multiple urls as input.

I’ll open an issue for this and have a peek, but I agree the logic you’re pointing to seems contradicting one another (input type vs ParseInput call)

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3

Hey @Ardeshir_Talaei!

Got a chance to check this out today. Turns out that, even though the component doesn’t explicitly say so, it wasn’t really designed to pull more than one stream url at a time. Not sure where I got the idea they received multiple stream urls… :man_facepalming:t3:

The resulting multiple objects is in fact a bug, as this should not be allowed in the first place… And a warning should be displayed to clearly specify what’s happening.

Ideally, it would be nice to be able to pull multiple objects at once, but that would require a bit of a re-write of the current implementation, which is not something we had planned.

Mainly, it would most likely loose the ability to re-receive automatically whenever someone pushes a new commit. So it’s not something I’m happy just removing. :slight_smile:

Meanwhile, I’d be happy to continue this discussion and try to find a way to keep everyone happy :wink:

1 Like
4

Hey @AlanRynne , is there an update on this? Is there a way to pull more than one stream url at a time now?