I've created a bunch of wedge variations in TOPs and I want to flipbook each one, so i'm using a rop fetch pointing to an OpenGL Rop. This works fine, however it seems quite slow and it looks like Houdini is opening a separate hython instance for each work item. I think it would be more efficient to batch work items into groups of 10 for example and render that as a sequence. I've tried setting Frames Per Batch or All Frames in One Batch but it doesn't seem to work - the opengl rop is set to only render one frame so maybe thats the issue?

The ROP fetch's batching feature only works over a range of frames -- each batch will render the ROP by calling the ROP's render method over the full range specified on the node, instead of just for a single frame. If you're only rendering frame 1 for each work item, it's currently not possible to batch the work.

You could instead use Services though, which are a more general feature that creates a fixed pool of worker processes that get reused between work items: https://www.sidefx.com/docs/houdini/tops/services.html [www.sidefx.com]

Thanks for your reply. I didn't know about PDG services but i'll take a look. I was trying to trick the ROP fetch into thinking each work item is a frame by giving it a frame attribute but it wasn't fooled... Can you think of another workaround? From a quick glance at PDG services they look a bit overcomplicated for something that should be fairly simple. Is there a way to active a work item through a pre render frame python script? So rather than rendering a single frame I would set the number of frames to the number of work items and render it from rops rather than tops->rops. Seems a bit counterintuitive but might be the simplest option