[GitHub] [metron] nickwallen opened a new pull request #1559: METRON-2314 HDFSIndexingIntegrationTests Fails with SLF4J/Log4j Delegation Loop

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nickwallen opened a new pull request #1559: METRON-2314 HDFSIndexingIntegrationTests Fails with SLF4J/Log4j Delegation Loop
URL: https://github.com/apache/metron/pull/1559
 
 
   After merging #1557 from master into the `feature/METRON-2088-support-hdp-3.1` feature branch, the `HDFSIndexingIntegrationTest` fails.
   
   ```
   Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.185 sec <<< FAILURE! - in org.apache.metron.indexing.integration.HDFSIndexingIntegrationTest
   test(org.apache.metron.indexing.integration.HDFSIndexingIntegrationTest)  Time elapsed: 0.177 sec  <<< ERROR!
   java.lang.ExceptionInInitializerError
   	at java.lang.Class.forName0(Native Method)
   	at java.lang.Class.forName(Class.java:264)
   	at org.slf4j.impl.Log4jLoggerFactory.<clinit>(Log4jLoggerFactory.java:48)
   	...
   Caused by: java.lang.IllegalStateException: Detected both log4j-over-slf4j.jar AND slf4j-log4j12.jar on the class path, preempting StackOverflowError. See also http://www.slf4j.org/codes.html#log4jDelegationLoop for more details.
   	at org.apache.log4j.Log4jLoggerFactory.<clinit>(Log4jLoggerFactory.java:49)
   	... 37 more
   
   Results :
   
   Tests in error:
     HDFSIndexingIntegrationTest>IndexingIntegrationTest.test:72->BaseIntegrationTest.getKafkaComponent:29 » ExceptionInInitializer
   ```
   
   ### Root Cause
   
   It doesn't make sense for a project to pull-in both `slf4j-log4j12` and `log4j-over-slf4j`. The purpose of `slf4j-log4j12` is intended to redirect calls made to an SLF4J logger to Log4j. The purpose of `log4j-over-slf4j` is to redirect calls made to a Log4j logger to SLF4J. Pulling in both would cause endless indirection except for the specific check for this error performed by SLF4j.  See  [the SLF4j documentation here](http://www.slf4j.org/codes.html#log4jDelegationLoop) for more information.
   
   The `metron-indexing-storm` project was pulling in `log4j-over-slf4j` incorrectly as a transitive.  This needs to be explicitly excluded.
   
   ### Acceptance Testing
   
   The integration tests should pass.
   
   
   ### Pull Request Checklist
   
   - [ ] Is there a JIRA ticket associated with this PR? If not one needs to be created at [Metron Jira](https://issues.apache.org/jira/browse/METRON/?selectedTab=com.atlassian.jira.jira-projects-plugin:summary-panel).
   - [ ] Does your PR title start with METRON-XXXX where XXXX is the JIRA number you are trying to resolve? Pay particular attention to the hyphen "-" character.
   - [ ] Has your PR been rebased against the latest commit within the target branch (typically master)?
   

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