Thanks Jose Luis López for your insight here, would you
mind to apply for a JIRA account then file a new JIRA to follow
this issue? Please tell me your account name when you submit
application, and I would like to approve it on time.

Best Regards,
- He Xiaoqiao

On Fri, Jul 31, 2026 at 3:36 PM Jose Luis López López <[email protected]>
wrote:

> While analyzing HDFS-17951, I found that many tests leak mini-cluster
> instances (MiniDFSCluster, MiniQJMHACluster, MiniJournalCluster,
> MiniRouterDFSCluster, MiniYARNCluster, MiniMRYarnCluster and variants).
>
> A static scan of the test sources — vetted by hand to remove false
> positives such as clusters owned by harnesses or torn down through wrapper
> objects — found 86 cases in ~60 files, in three categories:
>   A) 27 tests create a local cluster and never shut it down on any path.
>
>   B) 38 tests shut the cluster down only on the happy path (no finally /
>  try-with-resources), so the cluster leaks exactly when the test fails.
>
>   C) 21 classes hold a cluster in a field with no teardown in the class
> or its superclasses.
>
> Impact: leaks stay within the class, but a leaked cluster keeps CI
> resources under the remaining tests, and one failure can cascade into bogus
> failures of later tests in the class.There is no impact on production, only
> improvement for CI testing.
>
> Please open a JIRA for this, and I will be happy to contribute.
>
> Regards,
> Jose Luis López
>

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