Understanding Intermitent Failures

Oct 13, 2025 by pynkocean.com 35 views

Introduction

Continuous Integration (CI) is a crucial aspect of software development, enabling teams to automate testing, build, and deployment processes. However, intermittent failures on the CI can be frustrating and time-consuming to resolve. In this article, we will delve into the world of intermittent failures on the CI, exploring common causes, and providing actionable insights to help you troubleshoot and resolve these issues.

Understanding Intermitent Failures

Intermitent failures on the CI occur when automated tests or builds fail intermittently, without a clear pattern or cause. These failures can be caused by a variety of factors, including:

Environmental factors: Changes in the environment, such as network connectivity, disk space, or system resources, can cause intermittent failures.
Code changes: Changes to the codebase can introduce new bugs or dependencies, leading to intermittent failures.
Dependency issues: Conflicts or incompatibilities between dependencies can cause intermittent failures.
Test flakiness: Flaky tests can cause intermittent failures, especially if they are not properly isolated or mocked.

Case Study 1: `FAILED tests/integration/cli/test_execute.py::test_pipe_nbconvert_execute`

The first intermittent failure we will examine is caused by a RuntimeError: Kernel didn't respond in 60 seconds at https://github.com/mwouts/jupytext/actions/runs/13697163074/job/38302272799. This failure is related to the test_pipe_nbconvert_execute test in the tests/integration/cli module.

Analysis

Upon analyzing the test failure, we notice that the test is attempting to execute a notebook using the nbconvert tool. The RuntimeError suggests that the kernel failed to respond within the specified time limit. This could be caused by a variety of factors, including:

Kernel configuration: The kernel configuration may be set to a high timeout value, causing the test to fail.
Dependency issues: Conflicts or incompatibilities between dependencies, such as nbconvert and jupyter, can cause the kernel to fail.
Test flakiness: The test may be flaky, causing it to fail intermittently.

Case Study 2: A `trusted` entry might remain after the notebook is un-trusted

The second intermittent failure we will examine is related to a trusted entry remaining after the notebook is un-trusted. This issue is reported in the tests/functional/others/test_trust_notebook.py module.

Analysis

Upon analyzing the test failure, we notice that the test is attempting to un-trust a notebook, but a trusted entry remains. This could be caused by a variety of factors, including:

Data corruption: Data corruption in the notebook or its metadata can cause the trusted entry to remain.
Dependency issues: Conflicts or incompatibilities between dependencies, such as jupyter and nbformat, can cause the trusted entry to remain.
Test flakiness: The test may be flaky, causing it to fail intermittently.

Case Study 3: `Error: Codecov: Failed to properly upload`

The third intermittent failure we will examine is related to a Error: Codecov: Failed to properly upload issue. This issue is reported in the tests/functional/others/test_trust_notebook.py module.

Analysis

Upon analyzing the test failure, we notice that the test is attempting to upload a coverage report to Codecov, but the upload fails. This could be caused by a variety of factors, including:

Network connectivity: Network connectivity issues can cause the upload to fail.
Dependency issues: Conflicts or incompatibilities between dependencies, such as codecov and requests, can cause the upload to fail.
Test flakiness: The test may be flaky, causing it to fail intermittently.

Conclusion

Intermitent failures on the CI can be frustrating and time-consuming to resolve. By understanding the common causes of these failures, including environmental factors, code changes, dependency issues, and test flakiness, we can take proactive steps to troubleshoot and resolve these issues. In this article, we examined three case studies of intermittent failures on the CI, including a RuntimeError: Kernel didn't respond in 60 seconds, a trusted entry remaining after the notebook is un-trusted, and a Error: Codecov: Failed to properly upload issue. By applying the insights and analysis provided in this article, you can improve your CI pipeline's reliability and reduce the occurrence of intermittent failures.

Recommendations

To improve your CI pipeline's reliability and reduce the occurrence of intermittent failures, we recommend the following:

Monitor your CI pipeline: Regularly monitor your CI pipeline to detect intermittent failures and identify their causes.
Analyze test failures: Analyze test failures to identify the root cause of the issue and take corrective action.
Improve test flakiness: Improve test flakiness by isolating and mocking dependencies, and using techniques such as retrying and timeouts.
Update dependencies: Regularly update dependencies to ensure compatibility and avoid conflicts.
Test in isolation: Test in isolation to ensure that tests are not dependent on external factors.

Introduction

In our previous article, we explored the world of intermittent failures on the CI, examining common causes and providing actionable insights to help you troubleshoot and resolve these issues. In this article, we will answer some of the most frequently asked questions (FAQs) related to intermittent failures on the CI.

Q: What are intermittent failures on the CI?

A: Intermitent failures on the CI occur when automated tests or builds fail intermittently, without a clear pattern or cause. These failures can be caused by a variety of factors, including environmental factors, code changes, dependency issues, and test flakiness.

Q: Why do intermittent failures occur on the CI?

A: Intermitent failures can occur on the CI due to a variety of reasons, including:

Environmental factors: Changes in the environment, such as network connectivity, disk space, or system resources, can cause intermittent failures.
Code changes: Changes to the codebase can introduce new bugs or dependencies, leading to intermittent failures.
Dependency issues: Conflicts or incompatibilities between dependencies can cause intermittent failures.
Test flakiness: Flaky tests can cause intermittent failures, especially if they are not properly isolated or mocked.

Q: How can I identify the root cause of an intermittent failure on the CI?

A: To identify the root cause of an intermittent failure on the CI, follow these steps:

Monitor your CI pipeline: Regularly monitor your CI pipeline to detect intermittent failures and identify their causes.
Analyze test failures: Analyze test failures to identify the root cause of the issue and take corrective action.
Improve test flakiness: Improve test flakiness by isolating and mocking dependencies, and using techniques such as retrying and timeouts.
Update dependencies: Regularly update dependencies to ensure compatibility and avoid conflicts.
Test in isolation: Test in isolation to ensure that tests are not dependent on external factors.

Q: How can I prevent intermittent failures on the CI?

A: To prevent intermittent failures on the CI, follow these best practices:

Write robust tests: Write robust tests that are not dependent on external factors.
Improve test flakiness: Improve test flakiness by isolating and mocking dependencies, and using techniques such as retrying and timeouts.
Update dependencies: Regularly update dependencies to ensure compatibility and avoid conflicts.
Monitor your CI pipeline: Regularly monitor your CI pipeline to detect intermittent failures and identify their causes.
Test in isolation: Test in isolation to ensure that tests are not dependent on external factors.

Q: What are some common causes of intermittent failures on the CI?

A: Some common causes of intermittent failures on the CI include:

Kernel configuration: The kernel configuration may be set to a high timeout value, causing the test to fail.
Dependency issues: Conflicts or incompatibilities between dependencies, such as nbconvert and jupyter, can cause the kernel to fail.
Test flakiness: The test may be flaky, causing it to fail intermittently.
Data corruption: Data corruption in the notebook or its metadata can cause the trusted entry to remain.
Network connectivity: Network connectivity issues can cause the upload to fail.

Q: How can I troubleshoot intermittent failures on the CI?

A: To troubleshoot intermittent failures on the CI, follow these steps:

Monitor your CI pipeline: Regularly monitor your CI pipeline to detect intermittent failures and identify their causes.
Analyze test failures: Analyze test failures to identify the root cause of the issue and take corrective action.
Improve test flakiness: Improve test flakiness by isolating and mocking dependencies, and using techniques such as retrying and timeouts.
Update dependencies: Regularly update dependencies to ensure compatibility and avoid conflicts.
Test in isolation: Test in isolation to ensure that tests are not dependent on external factors.

Conclusion

Intermitent failures on the CI can be frustrating and time-consuming to resolve. By understanding the common causes of these failures, identifying the root cause, and taking proactive steps to troubleshoot and resolve these issues, you can improve your CI pipeline's reliability and reduce the occurrence of intermittent failures. We hope this Q&A guide has provided you with the insights and knowledge you need to tackle intermittent failures on the CI.