perf: trim static scope map allocation#837
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stephenamar-db merged 1 commit intoMay 11, 2026
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Motivation: Reduce allocation overhead in the static expression transform scope setup without changing optimizer semantics. Modification: Build the immutable scope mapping with a direct while loop instead of zipWithIndex/map intermediate tuples and arrays. Result: Optimizer setup keeps the same immutable-scope behavior while doing less temporary allocation.
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Motivation:
Reduce optimizer allocation overhead in static scope construction without changing name-resolution semantics.
Key Design Decision:
Keep the existing immutable scope representation and only replace intermediate collection construction with a direct loop.
Modification:
ScopedExprTransformnow builds the child scope mapping with a while loop instead ofzipWithIndex.map, avoiding tuple and intermediate collection allocation.Benchmark Results:
OptimizerBenchmark.mainJMH0.432 +/- 0.004 ms/op0.422 +/- 0.004 ms/op-2.31%realistic2.jsonnet83.438 +/- 1.304 ms83.871 +/- 1.111 ms+0.52%Analysis:
This is intentionally smaller than the historical mutable-scope idea; it keeps the safer immutable invariant while trimming hot setup work. The Native CLI guard does not show a material end-to-end win, but the targeted optimizer benchmark is positive.
References:
Source exploration commit: He-Pin/sjsonnet
b1a42ad8.Result:
Local
./mill --no-server -j 1 __.reformatand./mill --no-server -j 1 __.testpassed on this split branch (2066/2066).