启动spark-shell时，“已经注册”WARN消息是什么？

Question

我在windows下安装了spark/hadoop。当我执行spark-shell时，我得到这些“已经注册”的警告。

我不知道这是否是我需要担心

C:\Users\Administrator\spark-2.2.0-bin-hadoop2.7\bin>spark-shell 
Using Spark's default log4j profile: org/apache/spark/log4j defaults.properties 
Setting default log level to "WARN". 
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel). 
17/09/24 14:29:15 WARN General: Plugin (Bundle) "org.datanucleus.store.rdbms" is already registered. Ensure you dont have multiple JAR versions of the same plugin in the 
classpath. The URL "file:/C:/Users/Administrator/spark-2.2.0-bin-hadoop2.7/bin/../jars/datanucleus-rdbms-3.2.9.jar" is already registered, and you are trying to registe 
r an identical plugin located at URL "file:/C:/Users/Administrator/spark-2.2.0-bin-hadoop2.7/jars/datanucleus-rdbms-3.2.9.jar." 
17/09/24 14:29:15 WARN General: Plugin (Bundle) "org.datanucleus" is already registered. Ensure you dont have multiple JAR versions of the same plugin in the classpath. 
The URL "file:/C:/Users/Administrator/spark-2.2.0-bin-hadoop2.7/jars/datanucleus-core-3.2.10.jar" is already registered, and you are trying to register an identical plug 
in located at URL "file:/C:/Users/Administrator/spark-2.2.0-bin-hadoop2.7/bin/../jars/datanucleus-core-3.2.10.jar." 
17/09/24 14:29:15 WARN General: Plugin (Bundle) "org.datanucleus.api.jdo" is already registered. Ensure you dont have multiple JAR versions of the same plugin in the cla 
sspath. The URL "file:/C:/Users/Administrator/spark-2.2.0-bin-hadoop2.7/jars/datanucleus-api-jdo-3.2.6.jar" is already registered, and you are trying to register an iden 
tical plugin located at URL "file:/C:/Users/Administrator/spark-2.2.0-bin-hadoop2.7/bin/../jars/datanucleus-api-jdo-3.2.6.jar." 
17/09/24 14:29:19 WARN ObjectStore: Failed to get database global_temp, returning NoSuchObjectException 
Spark context Web UI available at http://173.198.192.78:4040 
Spark context available as 'sc' (master = local[*], app id = local-1506277753081). 
Spark session available as 'spark'. 
Welcome to 
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Answer 1

这是一个警告，以确保不在同一类路径中的多个罐子。 “已经注册”意味着类路径中的jar被注册并且应用程序正在尝试注册。这是没有什么可担心的，如果你不希望看到这个设置日志级别为ERROR。