Polling with a Smaller Interval

Oct 13, 2025 by wbrum.org 66 views

Problem Statement

The current implementation of KDS sync unit tests introduces a 5-second wait time before checking golden files to avoid flakiness. This was initially added as a quick fix in PR #13100, but it seems unnecessary in most cases and significantly slows down the tests.

Understanding the Issue

The primary concern with the current implementation is the inconsistent wait time. The 5-second wait time is arbitrary and may not be sufficient in all scenarios. This can lead to flakiness in the tests, making it challenging to identify and fix issues. Moreover, the wait time can be a significant bottleneck in the testing process, slowing down the overall development cycle.

Identifying a Better Approach

To address this issue, we need to find a more reliable and efficient way to check if the sync is complete without relying on a fixed sleep time. Here are some potential approaches to consider:

1. Polling with a Smaller Interval

Instead of waiting for 5 seconds, we can implement a polling mechanism with a smaller interval, such as 100-200 milliseconds. This will allow us to check for the completion of the sync more frequently, reducing the likelihood of flakiness.

2. Using a More Robust Condition

We can introduce a more robust condition to check for the completion of the sync. For example, we can verify that the expected data is present in the golden files, or that the sync has reached a stable state.

3. Implementing a Timeout Mechanism

We can implement a timeout mechanism that will terminate the test if the sync does not complete within a reasonable time frame. This will prevent the test from hanging indefinitely and allow us to identify issues more efficiently.

Designing a Solution

To design a solution that addresses the issue of the 5-second wait time, we need to consider the following factors:

1. Test Reliability

We need to ensure that the tests are reliable and produce consistent results. This can be achieved by introducing a more robust condition to check for the completion of the sync.

2. Test Efficiency

We need to minimize the time it takes to run the tests. This can be achieved by implementing a polling mechanism with a smaller interval or using a timeout mechanism.

3. Test Maintainability

We need to make the tests more maintainable by introducing a more flexible and adaptable solution. This can be achieved by using a more robust condition or implementing a timeout mechanism.

Implementing a Solution

To implement a solution that addresses the issue of the 5-second wait time, we can follow these steps:

1. Introduce a Polling Mechanism

We can introduce a polling mechanism that checks for the completion of the sync at regular intervals. This can be achieved by using a smaller interval, such as 100-200 milliseconds.

2. Implement a Timeout Mechanism

We can implement a timeout mechanism that will terminate the test if the sync does not complete within a reasonable time frame. This can be achieved by using a library or framework that provides a timeout mechanism.

3. Verify the Expected Data

We can verify that the expected data is present in the golden files. This can be achieved by using a library or framework that provides a data verification mechanism.

Example Code

Here is an example code snippet that demonstrates how to implement a polling mechanism with a smaller interval:

public class KdsSyncTest {
    @Test
    public void testKdsSync() {
        // Initialize the KDS sync
        KdsSync kdsSync = new KdsSync();

        // Set the polling interval to 100 milliseconds
        kdsSync.setPollingInterval(100);

        // Start the KDS sync
        kdsSync.start();

        // Wait for the sync to complete
        while (!kdsSync.isComplete()) {
            // Poll the sync every 100 milliseconds
            kdsSync.poll();
        }

        // Verify the expected data
        verifyExpectedData(kdsSync.getGoldenFiles());
    }
}

Conclusion

Q&A: Improving KDS Sync Unit Tests

Q: What is the current issue with KDS sync unit tests?

A: The current implementation of KDS sync unit tests introduces a 5-second wait time before checking golden files to avoid flakiness. This was initially added as a quick fix, but it seems unnecessary in most cases and significantly slows down the tests.

Q: Why is the 5-second wait time a problem?

A: The 5-second wait time is arbitrary and may not be sufficient in all scenarios. This can lead to flakiness in the tests, making it challenging to identify and fix issues. Moreover, the wait time can be a significant bottleneck in the testing process, slowing down the overall development cycle.

Q: What are some potential approaches to address the issue?

A: Some potential approaches to address the issue include:

Polling with a smaller interval: Instead of waiting for 5 seconds, we can implement a polling mechanism with a smaller interval, such as 100-200 milliseconds.
Using a more robust condition: We can introduce a more robust condition to check for the completion of the sync, such as verifying that the expected data is present in the golden files.
Implementing a timeout mechanism: We can implement a timeout mechanism that will terminate the test if the sync does not complete within a reasonable time frame.

Q: What are the benefits of implementing a polling mechanism with a smaller interval?

A: Implementing a polling mechanism with a smaller interval can help to:

Reduce flakiness: By checking for the completion of the sync more frequently, we can reduce the likelihood of flakiness.
Improve test efficiency: By reducing the wait time, we can make the tests more efficient and reduce the overall testing time.
Increase test reliability: By introducing a more robust condition, we can increase the reliability of the tests and make them more maintainable.

Q: What are the benefits of implementing a timeout mechanism?

A: Implementing a timeout mechanism can help to:

Prevent test hangs: By terminating the test if the sync does not complete within a reasonable time frame, we can prevent test hangs and make the tests more reliable.
Improve test efficiency: By reducing the wait time, we can make the tests more efficient and reduce the overall testing time.
Increase test maintainability: By introducing a timeout mechanism, we can make the tests more maintainable and easier to debug.

Q: How can we verify the expected data in the golden files?

A: We can verify the expected data in the golden files by using a library or framework that provides a data verification mechanism. This can include:

JSON schema validation: We can use a JSON schema validation library to verify that the expected data is present in the golden files.
Data comparison: We can use a data comparison library to verify that the expected data is present in the golden files.
Custom verification logic: We can implement custom verification logic to verify that the expected data is present in the golden files.

Q: What are some best practices for implementing a polling mechanism with a smaller interval?

A: Some best practices for implementing a polling mechanism with a smaller interval include:

Use a consistent polling interval: We should use a consistent polling interval to ensure that the tests are reliable and efficient.
Use a robust condition: We should use a robust condition to check for the completion of the sync to ensure that the tests are reliable and maintainable.
Monitor test performance: We should monitor test performance to ensure that the tests are efficient and reliable.

Q: What are some best practices for implementing a timeout mechanism?

A: Some best practices for implementing a timeout mechanism include:

Use a reasonable timeout value: We should use a reasonable timeout value to ensure that the tests are efficient and reliable.
Use a robust condition: We should use a robust condition to check for the completion of the sync to ensure that the tests are reliable and maintainable.
Monitor test performance: We should monitor test performance to ensure that the tests are efficient and reliable.

Conclusion

In conclusion, the current implementation of KDS sync unit tests introduces a 5-second wait time that can lead to flakiness and slow down the tests. To address this issue, we need to find a more reliable and efficient way to check if the sync is complete without relying on a fixed sleep time. By implementing a polling mechanism with a smaller interval, using a more robust condition, and verifying the expected data, we can design a solution that addresses the issue of the 5-second wait time and makes the tests more reliable, efficient, and maintainable.