Delay creating metadata in dask.to_cloudvolume #309
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william-silversmith merged 2 commits intoseung-lab:masterfrom Jan 20, 2020
chrisroat:delay_metadata
Merged
Delay creating metadata in dask.to_cloudvolume #309william-silversmith merged 2 commits intoseung-lab:masterfrom chrisroat:delay_metadata
william-silversmith merged 2 commits intoseung-lab:masterfrom
chrisroat:delay_metadata
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I've updated this PR to always "delay" the initial creation of info and provenance metadata. In reality, all this does is create a dependency such that the metadata is written prior to the data. It simply moves metadata creation to compute-time instead of during dask graph-computation time. For immediate computation, this shouldn't show an effect. For delayed computation, this will move the creation to a worker. I think it is ready to go. The travis failure seems unrelated. |
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lgtm, tests pass when running with the appropriate credentials |
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I was finding a huge slowdown when opening many volumes for writing on a cloud filesystem. All the metadata files were being written from my machine -- instead of being sharded to workers.
In addition, when compute=False, it may not be the intention of the caller to ever write out data. The PR delays the writing of
infoorprovenanceuntil compute time.For these reasons, I think we can delay writing the metadata. It's an open question to me if we should always wrap in
dask.delayed, regardless of the value of compute. I believe this may be better, and am trying to open a discussion with the dask maintainers on a similar PR in their repo - dask/dask#5797