[NIFI-9417] Flaky BulletinMergerTest.java

• Type: Bug
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Fix Version/s: 1.16.0, 1.15.1
• Environment: Maven 3.6.0, Java 1.8.0_292
• Assignee: Unassigned
• Reporter: Yiming Li
• Created: 29/Nov/21 00:45
• Updated: 16/Dec/21 19:54
• Resolved: 09/Dec/21 18:32

Description

SHA: 5aced2b4bc66d2dd85b1507755fff2b1fb8c4a64

The hashmap does not have a guaranteed iteration order, in the process of BulletinMerger.mergeBulletins() (line-78), the order of [copyOfBulletin1, bulletinEntity1] in the list can be eithter copyOfBulletin1 first or bulletinEntity1 first. The mergeBulletins() will keep the most recent bulletin with the larger time, and because all BulletinEntity are created from the function {}createBulletin()(line-38) and have the same time property in this test, mergeBulletins() will just keep the first in the list. So sometimes bulletinEntity1 will be returned instead of copyOfBulletin1, which results in the failure (line-80): assertTrue(bulletinEntities.contains(copyOfBulletin1));

The proposed fix is replacing LinkedHashMap with Hashmap to insure the determinism. After this change, the order will always be bulletinEntity1 before the copyOfBulletin1 and the merge results will always contain bulletinEntity1 instead of copyOfBulletin1. So I also change the assertion to assertTrue(bulletinEntities.contains(bulletinEntity1);

Tentative Pull Request: https://github.com/LeoYimingLi/nifi/pull/1/files

 

The way to reproduce the flaky test failure:
 0.Environment setup: Maven 3.6.0 and Java 1.8.0_292
 1.clone the repo:
  git clone https://github.com/spring-projects/spring-data-cassandra
  cd spring-data-cassandra
  git checkout 5aced2b4bc66d2dd85b1507755fff2b1fb8c4a64

 2.run with [Nondex tool](https://github.com/TestingResearchIllinois/NonDex) (which explores different behaviors of under-determined APIs and reports test failures)

  mvn install -pl nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-cluster -am -DskipTests

  mvn -pl nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-framework-cluster edu.illinois:nondex-maven-plugin:1.1.2:debug -Dtest=org.apache.nifi.cluster.manager.BulletinMergerTest#mergeBulletins
 
  3.then we can get the test failure:

----------

[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR]   BulletinMergerTest.mergeBulletins:80 expected [true] but found [false]
[INFO] 
[ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0

-----------

And BulletinMergerTest.mergeBulletins line-80 is :

assertTrue(bulletinEntities.contains(copyOfBulletin1));

in this case, the bulletinEntities did not contain copyOfBulletin1 but bulletinEntity1.

 

 

Issue Links

• causes: NIFI-9495 Correct Intermittent BulletinMergerTest Failures
• links to: GitHub Pull Request #5572