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fix: Use thread context classloader for Iceberg class loading #3738

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Merged
andygrove merged 1 commit into from
Mar 20, 2026
+40 −26
Merged

fix: Use thread context classloader for Iceberg class loading #3738

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35 changes: 26 additions & 9 deletions spark/src/main/scala/org/apache/comet/iceberg/IcebergReflection.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,29 @@ object IcebergReflection extends Logging {
val UNKNOWN = "unknown"
}

/**
* Loads a class using the thread context classloader first, then falls back to the system
* classloader.
*
* @param className
* Fully qualified class name to load
* @return
* The loaded Class object
*/
def loadClass(className: String): Class[_] = {
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@parthchandra parthchandra Mar 19, 2026

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If there is a class loading error, it would be useful to log which loader was used.

val classLoader = Thread.currentThread().getContextClassLoader
if (classLoader != null) {
// scalastyle:off classforname
Class.forName(className, true, classLoader)
// scalastyle:on classforname
} else {
// Fallback to default classloader if context classloader is null
// scalastyle:off classforname
Class.forName(className)
// scalastyle:on classforname
}
}

/**
* Searches through class hierarchy to find a method (including protected methods).
*/
Expand Down Expand Up @@ -124,9 +147,7 @@ object IcebergReflection extends Logging {
*/
def extractFileLocation(file: Any): Option[String] = {
try {
// scalastyle:off classforname
val contentFileClass = Class.forName(ClassNames.CONTENT_FILE)
// scalastyle:on classforname
val contentFileClass = loadClass(ClassNames.CONTENT_FILE)
extractFileLocation(contentFileClass, file)
} catch {
case _: Exception => None
Expand Down Expand Up @@ -387,9 +408,7 @@ object IcebergReflection extends Logging {
*/
def getEqualityFieldIds(deleteFile: Any): java.util.List[_] = {
try {
// scalastyle:off classforname
val deleteFileClass = Class.forName(ClassNames.DELETE_FILE)
// scalastyle:on classforname
val deleteFileClass = loadClass(ClassNames.DELETE_FILE)
val equalityFieldIdsMethod = deleteFileClass.getMethod("equalityFieldIds")
val ids = equalityFieldIdsMethod.invoke(deleteFile).asInstanceOf[java.util.List[_]]
if (ids == null) new java.util.ArrayList[Any]() else ids
Expand Down Expand Up @@ -515,9 +534,7 @@ object IcebergReflection extends Logging {
val fieldsMethod = partitionSpec.getClass.getMethod("fields")
val fields = fieldsMethod.invoke(partitionSpec).asInstanceOf[java.util.List[_]]

// scalastyle:off classforname
val partitionFieldClass = Class.forName(ClassNames.PARTITION_FIELD)
// scalastyle:on classforname
val partitionFieldClass = loadClass(ClassNames.PARTITION_FIELD)
val sourceIdMethod = partitionFieldClass.getMethod("sourceId")
val findFieldMethod = schema.getClass.getMethod("findField", classOf[Int])

Expand Down
31 changes: 14 additions & 17 deletions spark/src/main/scala/org/apache/comet/serde/operator/CometIcebergNativeScan.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -227,9 +227,7 @@ object CometIcebergNativeScan extends CometOperatorSerde[CometBatchScanExec] wit
fileScanTaskClass: Class[_],
fileIO: Option[Any]): Seq[OperatorOuterClass.IcebergDeleteFile] = {
try {
// scalastyle:off classforname
val deleteFileClass = Class.forName(IcebergReflection.ClassNames.DELETE_FILE)
// scalastyle:on classforname
val deleteFileClass = IcebergReflection.loadClass(IcebergReflection.ClassNames.DELETE_FILE)

val deletes = IcebergReflection.getDeleteFilesFromTask(task, fileScanTaskClass)

Expand Down Expand Up @@ -336,13 +334,11 @@ object CometIcebergNativeScan extends CometOperatorSerde[CometBatchScanExec] wit
if (spec != null) {
// Deduplicate partition spec
try {
// scalastyle:off classforname
val partitionSpecParserClass =
Class.forName(IcebergReflection.ClassNames.PARTITION_SPEC_PARSER)
IcebergReflection.loadClass(IcebergReflection.ClassNames.PARTITION_SPEC_PARSER)
val toJsonMethod = partitionSpecParserClass.getMethod(
"toJson",
Class.forName(IcebergReflection.ClassNames.PARTITION_SPEC))
// scalastyle:on classforname
IcebergReflection.loadClass(IcebergReflection.ClassNames.PARTITION_SPEC))
val partitionSpecJson = toJsonMethod
.invoke(null, spec)
.asInstanceOf[String]
Expand Down Expand Up @@ -685,9 +681,7 @@ object CometIcebergNativeScan extends CometOperatorSerde[CometBatchScanExec] wit
*/
private def convertIcebergLiteral(icebergLiteral: Any, sparkType: DataType): Literal = {
// Load Literal interface to get value() method (use interface to avoid package-private issues)
// scalastyle:off classforname
val literalClass = Class.forName(IcebergReflection.ClassNames.LITERAL)
// scalastyle:on classforname
val literalClass = IcebergReflection.loadClass(IcebergReflection.ClassNames.LITERAL)
val valueMethod = literalClass.getMethod("value")
val value = valueMethod.invoke(icebergLiteral)

Expand Down Expand Up @@ -790,13 +784,16 @@ object CometIcebergNativeScan extends CometOperatorSerde[CometBatchScanExec] wit
}

// Load Iceberg classes once (avoid repeated class loading in loop)
// scalastyle:off classforname
val contentScanTaskClass = Class.forName(IcebergReflection.ClassNames.CONTENT_SCAN_TASK)
val fileScanTaskClass = Class.forName(IcebergReflection.ClassNames.FILE_SCAN_TASK)
val contentFileClass = Class.forName(IcebergReflection.ClassNames.CONTENT_FILE)
val schemaParserClass = Class.forName(IcebergReflection.ClassNames.SCHEMA_PARSER)
val schemaClass = Class.forName(IcebergReflection.ClassNames.SCHEMA)
// scalastyle:on classforname
val contentScanTaskClass =
IcebergReflection.loadClass(IcebergReflection.ClassNames.CONTENT_SCAN_TASK)
val fileScanTaskClass =
IcebergReflection.loadClass(IcebergReflection.ClassNames.FILE_SCAN_TASK)
val contentFileClass =
IcebergReflection.loadClass(IcebergReflection.ClassNames.CONTENT_FILE)
val schemaParserClass =
IcebergReflection.loadClass(IcebergReflection.ClassNames.SCHEMA_PARSER)
val schemaClass =
IcebergReflection.loadClass(IcebergReflection.ClassNames.SCHEMA)

// Cache method lookups (avoid repeated getMethod in loop)
val fileMethod = contentScanTaskClass.getMethod("file")
Expand Down
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