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https://issues.apache.org/jira/browse/SPARK-59617?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-59617:
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Labels: pull-request-available (was: )
> Reuse a per-evaluator output buffer in JsonExpressionEvalUtils (json_tuple,
> JSON_TABLE)
> ---------------------------------------------------------------------------------------
>
> Key: SPARK-59617
> URL: https://issues.apache.org/jira/browse/SPARK-59617
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 4.1.0
> Reporter: David Mollitor
> Priority: Minor
> Labels: pull-request-available
>
> h3. Problem
> {{JsonExpressionEvalUtils}} has several JSON-extraction evaluators. Two
> already reuse a single instance buffer across rows:
> {{GetJsonObjectEvaluator}} and {{MultiGetJsonObjectEvaluator}} each hold
> {{@transient private lazy val outputBuffer = new ByteArrayOutputStream()}}
> and call
> {{outputBuffer.reset()}} before each use. The other two allocate a fresh
> {{ByteArrayOutputStream}} on every field/element:
> * {{JsonTupleEvaluator.parseRow}} -- a new buffer per extracted field
> (unbounded per row for a wide {{json_tuple(...)}}).
> * {{JsonTableEvaluator.serializeCurrentValue}} -- a new buffer per call; the
> hot caller expands a JSON array one element at a time.
> A no-arg {{ByteArrayOutputStream}} starts at the JDK default of 32 bytes and
> grows by doubling, so allocating (and then GC-ing) a fresh one per
> field/element is steady allocation churn on the json_tuple / JSON_TABLE
> evaluation path.
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