Use Taskspec fuse implementation #1162
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fjetter
commented
Nov 11, 2024
dask_expr/_expr.py
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| internal_tasks[t.key] = t | ||
| # The above is ambiguous and we have to cull to get an unambiguous graph | ||
| outkey = (self.exprs[0]._name, index) | ||
| work = [outkey] | ||
| internal_tasks_culled = [] | ||
| while work: | ||
| tkey = work.pop() | ||
| if tkey not in internal_tasks: | ||
| # External dependency | ||
| continue | ||
| t = internal_tasks[tkey] | ||
| internal_tasks_culled.append(t) | ||
| work.extend(t.dependencies) |
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All of this shouldn't be necessary if there weren't dead nodes
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Do you have an example with dead nodes? I am curious to see what's going on there
Note: The same is happening in dask/dask when trying to replace the SubgraphCallables :( |
|
I'ver removed the culling, things should be good to go now |
phofl
approved these changes
Nov 13, 2024
|
thanks |
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This is using the
Task.fuse(see dask/dask#11509) method for the Fused task. In theory this should've reduced complexity quite a bit but I encountered problems since the subgraphs are including dead nodes, i.e. there are expressions in_exprthat are no longer reachable if we walk the tasks. TheTask.fuseraises in such a case since it requires a subgraph that is uniquely reducing to a single task (I put that condition in to catch stuff like this).Adding an explicit culling step in advance fixes this so everything is OK. However, where is this redundant node coming from and can we get rid of this??
cc @phofl