YES PLEASE FOR A NEW CALLBACK! I'll add some further context to my desire to upvote this proposal. I am currently in the category of having to use 'loop kicking' (interesting term for it, but its what we have to do). We need to be able to run an event loop to capture msgs to our distributed rendering platform for blender. Msgs come back to blender from other nodes, currently we've had to use a modal operator with a timer to implement async operations. I got excited about asyncio a while back, but realised that it needed to have the same modal operator to work. If there was an event that could be subscribed to that would avoid the need to have a modal operator running this would be excellent. Modal operators when used for look kicking have some pretty undesirable drawbacks;

Hi Brecht,

First, thanks so much for the fast reply, I've been testing as you suggested and with the depth pass connected to the Z socket this works as you said it should. However, there is no mention of this fact in the documentation and I think it would save others a lot of head scratching if the docs simply announced what you wrote above.

The problem is compounded by the fact that the vector blur seems to work without the z pass connected, that coupled with no explanation of if in the docs meant it wasn't obvious that the Z input was the issue. So I've set the status to open, hope the documentation edit will help others not fall over their feet like I did :)

@Campbell Barton (campbellbarton) Hi! When I try running the above code as a script from the text editor in blender, I get this error in the system console:

@Lukas Stockner (lukasstockner97)
Hey there, hope you had a great Christmas and and are so far having a happy new year. I was very interested to see something finally happening with cycles network rendering. However, I'd like to also point out that we're already distributing a free addon that provides distributed rendering for cycles, works in AWS and works P2P. It is also cross platform out of the box. It even distribute the denoising pass so that all nodes do denoising on their own image tiles. We have a small online following, but it is growing.

Hi guys, and particularly @Campbell Barton (campbellbarton), @Sergey Sharybin (sergey) :D merry Christmas to you and the blender devs team :)

@Brian Cary (brinux) We're working on an addon to fix this, anticipate that the fix will be integrated into our addon end of June this year. Feel free to contact us if you'd like to test. We got snagged on this problem too but found there is a way round it, but it involves programming, so we're building this into our addon which does network rendering.

@Campbell Barton (campbellbarton) , different issue - no problem. Just seemed close enough to warrant re-opening this one rather than creating a whole new bug report.

Hi guys, using current release (see system info here->

I think there is sufficient information in the blender api, though I think the issue here is that the scene_handler_pre handler does something that is not expected by triggering constantly.

@Campbell Barton (campbellbarton) I like the approach of not adding this into 2.8 so we can find a way around this, more time would really be appreciated so we can perhaps work together to find a more acceptable way forward :D.

Hi, my comment regards the propsed changes to the scene_update_pre handler. To some extent I'm echoing Brendon's concerns - (repeated below).

Hi Joey, can you elaborate on "better options" Im working on a network rendering addon for blender at the moment, would be nice to know what the plans are regarding this feature.

Hi Arnaud, have been looking through this code, but not sure what you meant by your last comment. I am new to the blender cpp code. I did find this

Hi Arnaud, :D

Thanks for your comment. That is an important point. We've been wondering for a while how to get around the issue, here is what we're facing right now, it is as you described.

Still present in 2.78a , I guess this is not going away? We've encountered it whilst developing a network render addon similar to Netrender, except we do bucket rendering or frame splitting. For us, the ability read in a multilayer exr is rather critical since the work around by Arnoud above doesn;t work for us.