Max Gekk created SPARK-59782:
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Summary: Make spark.sql.codegen.hugeMethodLimit public or document
it as a tuning knob
Key: SPARK-59782
URL: https://issues.apache.org/jira/browse/SPARK-59782
Project: Spark
Issue Type: Improvement
Components: SQL
Affects Versions: 5.0.0
Reporter: Max Gekk
spark.sql.codegen.hugeMethodLimit is the only setting that acts on the JIT
cliff: HotSpot does not compile a method past 8000 bytes
(-XX:+DontCompileHugeMethods, on by default), so a whole-stage codegen stage
whose per-row method crosses it runs interpreted, typically several times
slower. Setting the limit to 8000 makes such a stage fall back to the
non-whole-stage path instead, and the config's own doc already suggests that
value on HotSpot.
The config is .internal(), yet SPARK-59774 names it in a user-facing WARN as
the remedy. Internal configs already appear as tuning knobs in
docs/sql-performance-tuning.md (spark.sql.files.openCostInBytes,
spark.sql.sources.parallelPartitionDiscovery.parallelism,
spark.sql.requireAllClusterKeysForCoPartition), so there is precedent either
way.
Proposal: either make spark.sql.codegen.hugeMethodLimit public, or keep it
internal and list it in the configuration tables of sql-performance-tuning.md
with a short explanation of the cliff and when to set it to 8000.
Context: https://github.com/apache/spark/pull/59020
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