| Interface | Description | 
|---|---|
| Clock | An interface to represent clocks, so that they can be mocked out in unit tests. | 
| CommandLineLoggingUtils | |
| CommandLineUtils | Contains basic command line parsing functionality and methods to parse some common Spark CLI
 options. | 
| JsonUtils | |
| KnownSizeEstimation | A trait that allows a class to give  SizeEstimatormore accurate size estimation. | 
| ListenerBus<L,E> | An event bus which posts events to its listeners. | 
| SparkClassUtils | |
| SparkErrorUtils | |
| SparkFileUtils | |
| SparkSerDeUtils | |
| TaskCompletionListener | :: DeveloperApi :: | 
| TaskFailureListener | :: DeveloperApi :: | 
| Class | Description | 
|---|---|
| AccumulatorContext | An internal class used to track accumulators by Spark itself. | 
| AccumulatorV2<IN,OUT> | The base class for accumulators, that can accumulate inputs of type  IN, and produce output of
 typeOUT. | 
| CausedBy | Extractor Object for pulling out the root cause of an error. | 
| ChildFirstURLClassLoader | A mutable class loader that gives preference to its own URLs over the parent class loader
 when loading classes and resources. | 
| ClosureCleaner | A cleaner that renders closures serializable if they can be done so safely. | 
| CollectionAccumulator<T> | An  accumulatorfor collecting a list of elements. | 
| CollectionsUtils | |
| DependencyUtils | |
| DoubleAccumulator | An  accumulatorfor computing sum, count, and averages for double precision
 floating numbers. | 
| EnumUtil | |
| HadoopFSUtils | Utility functions to simplify and speed-up file listing. | 
| IndylambdaScalaClosures | |
| InnerClosureFinder | |
| IntParam | An extractor object for parsing strings into integers. | 
| Iterators | |
| JsonProtocol | Serializes SparkListener events to/from JSON. | 
| LongAccumulator | An  accumulatorfor computing sum, count, and average of 64-bit integers. | 
| MemoryParam | An extractor object for parsing JVM memory strings, such as "10g", into an Int representing
 the number of megabytes. | 
| MethodIdentifier<T> | Helper class to identify a method. | 
| MutablePair<T1,T2> | :: DeveloperApi ::
 A tuple of 2 elements. | 
| MutableURLClassLoader | URL class loader that exposes the `addURL` method in URLClassLoader. | 
| ParentClassLoader | A class loader which makes some protected methods in ClassLoader accessible. | 
| ReturnStatementFinder | |
| RpcUtils | |
| SecurityUtils | Various utility methods used by Spark Security. | 
| SerializableConfiguration | Hadoop configuration but serializable. | 
| ShutdownHookManager | Various utility methods used by Spark. | 
| SignalUtils | Contains utilities for working with posix signals. | 
| SizeEstimator | :: DeveloperApi ::
 Estimates the sizes of Java objects (number of bytes of memory they occupy), for use in
 memory-aware caches. | 
| SparkExitCode | |
| SparkSchemaUtils | Utils for handling schemas. | 
| SparkShutdownHook | |
| SparkThreadUtils | |
| StatCounter | A class for tracking the statistics of a set of numbers (count, mean and variance) in a
 numerically robust way. | 
| ThreadUtils | |
| Utils | Various utility methods used by Spark. | 
| VersionUtils | Utilities for working with Spark version strings |