Q41. While installing NiFi, you get “java.lang.UnsupportedClassVersionError” , what could be the reason?
Ans: You generally get java.lang.UnsupportedClassVersionError when you have multiple version of java and you are using wrong java version to run the script.
Please run below before starting Nifi
|
export JAVA_HOME=<jdk path you want to use> |
Q42. Can you use the single installation of Ranger on the HDP, to be used with HDF?
Ans: Yes, you can use single Ranger installed on the HDP to manage HDF (separate installation) as well. However, The Ranger that is included with HDP will not include the service definition for NiFi, so it would need to be installed manually.
Q43. If, I want to execute a shell script, in the NiFi dataflow. How can I do that?
Ans: To execute shell script in the NiFi processor. Then you can use ExecuteProcess processor.
Q44. What is the solution, when your dataflow, is interacting with external system and network outage caused the FlowFile to go in failed relationship?
Ans: Attempt retry anytime you are dealing with an external system where failures resulting from things that are out of NiFi's control for example
- Network outages
- Destination systems have no disk space
- Destination has files of same name etc.
Q45. What do you mean by “Back pressure deadlock”?
Ans: Suppose you have a processor e.g. PublishJMS and you are publishing the message to a target queue. However, target queue is full and you FlowFile will be routed to the failure relationship. And for re-try, you will re-try the same failed FlowFile again and input backpressure connection/queue is getting filled up which can cause a backpressure deadlock. In this situation, PublishJMS will not be called at all any longer. Even when the JMS problem resolves, the whole thing stays deadlocked.
