Apache Spark 面试题与答案
问题 21. Explain the concept of a Spark task.
A task is the smallest unit of work in Spark, representing the execution of a transformation or action on a partition of data. Tasks are scheduled by the Spark Scheduler on Spark Executors.
Example:
val taskResult = executor.runTask(taskID, taskInfo)
问题 22. How does Spark handle data skewness in transformations like groupByKey?
Data skewness occurs when certain keys have significantly more data than others. Spark handles it by using techniques like data pre-partitioning or using advanced algorithms like map-side aggregation.
Example:
val skewedData = inputRDD.groupByKey(numPartitions)
问题 23. What is the purpose of the Spark MLlib library?
Spark MLlib is Spark's machine learning library, providing scalable implementations of various machine learning algorithms and tools for building and evaluating machine learning models.
Example:
val model = new RandomForestClassifier().fit(trainingData)
问题 24. How does Spark handle data locality optimization?
Spark aims to schedule tasks on nodes that have a copy of the data to minimize data transfer over the network. This is achieved by using data locality-aware task scheduling.
Example:
sparkConf.set("spark.locality.wait", "2s")
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