AWS EMR上Spark集群模式下ObjectMapper中的NullPointerException

Question

我在此行中得到nullpointer異常（在aws emr上以群集模式（紗線）運行spark），但在客戶端模式下運行良好（以master為本地）

Map<String, Object> json = (Map<String, Object>) mapper.readValue(line, Map.class);

這是執行程序的堆棧跟蹤：

18/04/17 12:33:16 ERROR executor.Executor: Exception in task 0.2 in stage 0.0 (TID 4)
java.lang.NullPointerException
    at com.fasterxml.jackson.databind.util.LRUMap.get(LRUMap.java:47)
    at com.fasterxml.jackson.databind.type.TypeFactory._fromClass(TypeFactory.java:707)
    at com.fasterxml.jackson.databind.type.TypeFactory._constructType(TypeFactory.java:387)
    at com.fasterxml.jackson.databind.type.TypeFactory.constructType(TypeFactory.java:354)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2161)

我正在使用以下依賴項：

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.9.5</version>
  <scope>compile</scope>
</dependency>

Answer 1

@Ernest Kiwele發現了問題。 這是因為我正在導入com.fasterxml.jackson.databind.ObjectMapper而不是com.cloudera.com.fasterxml.jackson.databind.ObjectMapper