[MAPREDUCE-7358] Clean shared state pollution to avoid flaky test testMR

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: test
• Assignee: Unassigned
• Reporter: Yang Chen
• Created: 09/Aug/21 10:01
• Updated: 11/Aug/21 15:05

Description

What is the purpose of this change

This PR is to fix a non-idempotent test:

org.apache.hadoop.mapred.TestClusterMRNotification.testMR

Why the test failed

The root cause for the failure is that this test does not clean NotificationServlet.counter at the end, which pollutes the shared state. It may be better to clean state pollutions so that some other tests won't fail in the future due to the shared state polluted by this test.

Reproduce test failure

Run the test twice in the same JVM.

Expected result

The test should run successfully without any failures.

Actual result

Failure from test run:

NotificationTestCase.testMR:174 expected:<2> but was:<8>

Fix

Clear the value of NotificationServlet.counter at the end of the test.

 

Link to PR: