Copilot commented on code in PR #12236: URL: https://github.com/apache/gluten/pull/12236#discussion_r3359968202
########## backends-velox/src/main/scala/org/apache/spark/sql/execution/SchemaJsonInternCache.scala: ########## @@ -0,0 +1,55 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.spark.sql.execution + +import org.apache.spark.sql.types.{DataType, StructType} + +import com.github.benmanes.caffeine.cache.{Cache, Caffeine} + +import java.nio.charset.StandardCharsets + +/** + * Process-local memoizer for `StructType <-> JSON` codec on the cached-batch hot path. Best-effort + * Caffeine LRU; eviction recomputes via the same pure codec, so misses are indistinguishable from + * the no-cache baseline. Thread-safety via Caffeine `get(key, mappingFunction)`. + */ +final private[execution] class SchemaJsonInternCache { + import SchemaJsonInternCache._ + + private val encodeCache: Cache[StructType, Array[Byte]] = + Caffeine.newBuilder.maximumSize(CAP).build[StructType, Array[Byte]]() + + private val decodeCache: Cache[String, StructType] = + Caffeine.newBuilder.maximumSize(CAP).build[String, StructType]() + + /** Returns the canonical UTF-8 JSON byte form of `schema`. */ + def encodeBytes(schema: StructType): Array[Byte] = + encodeCache.get(schema, k => k.json.getBytes(StandardCharsets.UTF_8)) + + /** Returns the canonical [[StructType]] parsed from `bytes` (UTF-8 JSON). */ + def decodeStructType(bytes: Array[Byte]): StructType = { + val key = new String(bytes, StandardCharsets.UTF_8) + decodeCache.get(key, k => DataType.fromJson(k).asInstanceOf[StructType]) + } +} + +private[execution] object SchemaJsonInternCache { + // 256 entries: <= ~8.5 MB retained even at 1000-field schemas (~33 KB JSON each). Verified by + // Section C working-set sweep of the FU-D7 bench harness; revisit if C1/C2 gates fail. Review Comment: The memory-retention comment here appears to significantly underestimate worst-case heap usage: both caches retain keys and values (StructType keys + JSON bytes on encode side; String keys + StructType values on decode side), so retained heap can be well above `256 * jsonBytes` in pathological cases. Consider rewording to avoid a specific MB bound unless it accounts for all retained objects. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
