perf: Add ReflectionCache for Iceberg serialization optimization [iceberg]#3558
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Shekharrajak wants to merge 3 commits intoapache:mainfrom
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perf: Add ReflectionCache for Iceberg serialization optimization [iceberg]#3558Shekharrajak wants to merge 3 commits intoapache:mainfrom
Shekharrajak wants to merge 3 commits intoapache:mainfrom
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mbutrovich
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Feb 20, 2026
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Thanks @Shekharrajak! First round of feedback. I need to dig into failure handling on this PR next week. Whenever you push your next commit we'll get coverage on the Iceberg tests.
spark/src/main/scala/org/apache/comet/serde/operator/CometIcebergNativeScan.scala
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spark/src/test/scala/org/apache/spark/sql/benchmark/CometIcebergSerializationBenchmark.scala
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spark/src/test/scala/org/apache/spark/sql/benchmark/CometIcebergSerializationBenchmark.scala
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spark/src/test/scala/org/apache/spark/sql/benchmark/CometIcebergSerializationBenchmark.scala
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spark/src/main/scala/org/apache/comet/iceberg/IcebergReflection.scala
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Shekharrajak
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Feb 21, 2026
| * Cache for Iceberg reflection metadata to avoid repeated class loading and method lookups. | ||
| * | ||
| * This cache is created once per serializePartitions() call and passed to helper methods. It | ||
| * provides ~50% serialization speedup by eliminating redundant reflection operations that would |
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Cache at the right scope - Create cache once per serializePartitions() call, not per-task and Pass cache to helpers: Don't let helper methods do their own class loading
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Which issue does this PR close?
Closes #3456.
Rationale for this change
PR #3298 added reflection caching optimizations for Iceberg serialization, but these were lost during subsequent refactoring in #3349 and #3443. The current code performs redundant
Class.forName()andgetMethod()calls for every task (tens of thousands of times for large tables), causing significant serialization overhead.What changes are included in this PR?
ReflectionCachecase classserializePartitions()to create cache once and pass to helper methodsextractDeleteFilesList()andserializePartitionData()to use cached methodsbuildFieldIdMapping()calls per-taskCometIcebergSerializationBenchmarkto measure serialization performanceHow are these changes tested?
Benchmark: