gengliangwang opened a new pull request, #57049:
URL: https://github.com/apache/spark/pull/57049
### What changes were proposed in this pull request?
Drop the `compile time (ms)` metric from `WholeStageCodegenSizeBenchmark`
(added in SPARK-57915),
and regenerate its results file. This removes the metric's docstring bullet,
the
`CodeGenerator.resetCompileTime()` / `compileTime` measurement, the reported
row, and the
now-unused `CodeGenerator` import.
### Why are the changes needed?
The compile-time number is not a reliable or reproducible metric, so it can
mislead when comparing
before/after:
- `CodeGenerator.compile` is wrapped in a cache keyed on the generated
source string, and
`compileTime` only accrues on cache misses. Across the TPC-DS suite a
large fraction of stages
generate identical source (measured: ~2247 stages but only ~1214 distinct
sources), so the metric
reflects the time to compile the *distinct* subset -- and that subset
differs between two versions,
so the totals are not comparable.
- The size-bounded cache (`spark.sql.codegen.cache.maxEntries`, default 100)
evicts and recompiles,
so the number also depends on eviction order, not just the code.
- It is wall-clock time and therefore JIT/GC/machine-load sensitive: the
same tree measured ~10%
apart across two runs, larger than the differences the benchmark is meant
to detect.
The remaining metrics (generated source size, summed/max method bytecode,
inner-class count,
constant-pool entries) are deterministic and machine-independent, and source
size is itself a stable
proxy for compile cost (roughly linear in input), so nothing actionable is
lost.
### Does this PR introduce _any_ user-facing change?
No (test-only benchmark).
### How was this patch tested?
Re-ran `build/sbt "sql/Test/runMain
org.apache.spark.sql.execution.benchmark.WholeStageCodegenSizeBenchmark"`
and regenerated
`sql/core/benchmarks/WholeStageCodegenSizeBenchmark-results.txt` with
`SPARK_GENERATE_BENCHMARK_FILES=1`; the compile-time row is gone and the
deterministic metrics are
unchanged.
### Was this patch authored or co-authored using generative AI tooling?
Generated-by: Claude Code (Opus 4.8)
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