Reduce hashing during v2 transitive graph walks#4109
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stuhood merged 2 commits intoDec 1, 2016
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…d a faster hashcode impl for HydratedTarget.
JieGhost
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Looks good! Remind me of a similar change I made in fs.py. What I found there is same to your finding, ie, using set is much faster than OrderedSet.
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### Problem Transitive graph walks in the v2 engine involve doing lots of deduping merges of collections of `HydratedTarget` objects. Pre-change, this was taking up about 70% of the total runtime of `./pants --enable-v2-engine list $target` for a highly connected `$target`. ### Solution OrderedSet is significantly slower for individual dedupe operations (particularly when it is converted back into a tuple afterward), so we switch to deduping a generator using a throwaway set and collecting it into a tuple. Additionally, because `HydratedTarget` objects are guaranteed to have an Address, we implement equality/hash checks using an Address lifted from the inner structs. ### Result The runtime of `./pants --enable-v2-engine list $target` is improved by approximately 2x.
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Problem
Transitive graph walks in the v2 engine involve doing lots of deduping merges of collections of
HydratedTargetobjects. Pre-change, this was taking up about 70% of the total runtime of./pants --enable-v2-engine list $targetfor a highly connected$target.Solution
OrderedSet is significantly slower for individual dedupe operations (particularly when it is converted back into a tuple afterward), so we switch to deduping a generator using a throwaway set and collecting it into a tuple.
Additionally, because
HydratedTargetobjects are guaranteed to have an Address, we implement equality/hash checks using an Address lifted from the inner structs.Result
The runtime of
./pants --enable-v2-engine list $targetis improved by approximately 2x.