MemoryStore类:https://github.com/apache/spark/blob/branch-2.4/core/src/main/scala/org/apache/spark/storage/memory/MemoryStore.scala,内存存储实现类。读、写操作。 DiskStore类结构:https://github.com/apache/spark/blob/branch-2.4/core/src/main/scala/org/apache/spark/storage/DiskStore.scala,磁盘存储...
SparkContext类:https://github.com/apache/spark/blob/branch-2.4/core/src/main/scala/org/apache/spark/SparkContext.scala,是broadcast使用的入口函数。 Broadcast接口类:https://github.com/apache/spark/blob/branch-2.4/core/src/main/scala/org/apache/spark/broadcast/Broadcast.scala,是broadcast包装类的接口...
A second abstraction in Spark isshared variablesthat can be used in parallel operations. By default, when Spark runs a function in parallel as a set of tasks on different nodes, it ships a copy of each variable used in the function to each task. Sometimes, a variable needs to be shared ...
spark.eventLog.enabled true spark.eventLog.dir hdfs://namenode/shared/spark-logs The history server can be configured as follows: Environment Variables Environment VariableMeaning SPARK_DAEMON_MEMORY Memory to allocate to the history server (default: 1g). SPARK_DAEMON_JAVA_OPTS JVM options for ...
Spark一个非常重要的特征就是共享变量。共享变量分为广播变量(broadcast variable)和累加器(Accumulators)。 广播变量可以在driver程序中写入,在executor端读取。 累加器在executors中写入,而在驱动程序(driver端)读取。 但本章只讲解broadcast变量 Spark官网“共享变量”简介请参考: ...