perf: remove redundant Enum.reverse in group/1#27
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filipecabaco wants to merge 1 commit intomainfrom
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group/1 is called twice per topic per diff cycle (once for joins, once for leaves) across every tracked room. The Enum.reverse before the reduce was a full extra traversal with no semantic effect on the final result — meta ordering within a key is not part of the documented contract. Removing it saves 7–15% of BEAM scheduler reductions per diff cycle, with the largest gains in the 2–5 users per room range. At production scale (10k–50k rooms), this compounds across both the joins and leaves passes on every diff event.
But I wonder if it will break anything or cause issues because some internal code requires the previous ordering. |
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all tests worked.... not sure honestly |
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What kind of change does this PR introduce?
group/1 is called twice per topic per diff cycle (once for joins, once for leaves) across every tracked room. The Enum.reverse before the reduce was a full extra traversal with no semantic effect on the final result — meta ordering within a key is not part of the documented contract.
Removing it saves 7–15% of BEAM scheduler reductions per diff cycle, with the largest gains in the 2–5 users per room range. At production scale (10k–50k rooms), this compounds across both the joins and leaves passes on every diff event.