Introduction
Understanding retries and working with them plays a very crucial role in dealing with flaky tests. You need to avoid overloading systems with too many retries while ensuring your tests remain reliable. This is where the Circuit Breaker pattern comes into play.
What is the Circuit Breaker Pattern?
The Circuit Breaker pattern is inspired by the concept of electrical circuits. Just like a circuit breaker in an electrical system stops the flow of electricity to prevent damage during an overload, the Circuit Breaker pattern helps manage retries in software by:
- Monitoring Failures: Tracking the number of consecutive failures.
- Opening the Circuit: Stopping further retries after reaching a specified number of failures to avoid putting extra strain on the system.
- Cooldown Period: Introducing a pause or delay before allowing any new retry attempts.
- Resetting the Circuit: If no additional failures occur during the cooldown period, the retry mechanism is reset to allow future attempts.
Implementing the Circuit Breaker Pattern in Katalon Studio
Katalon Studio, allows for implementing sophisticated retry mechanisms like the Circuit Breaker pattern. Here’s a step-by-step example of how you can set it up:
int attempts = 0
int maxAttempts = 3
int circuitOpen = 0
int circuitResetTime = 10000 // Cooldown period of 10 seconds
while (attempts < maxAttempts) {
try {
WebUI.click(findTestObject(‘Page_Opportunity/button_Save’))
break
} catch (Exception e) {
attempts++
if (attempts == maxAttempts) {
circuitOpen++
WebUI.delay(circuitResetTime / 1000) // Wait for the cooldown period
attempts = 0 // Reset attempt counter after cooldown
} else {
WebUI.delay(2000) // Short delay between retries
}
}
}
if (circuitOpen > 0) {
throw new StepFailedException(“Circuit breaker activated. Failed to click Save button.”)
}
Practical Scenarios for Using the Circuit Breaker Pattern
1. Handling System Overload
Scenario: When your web application is under heavy load, continuous retries might worsen the situation. The Circuit Breaker pattern helps by stopping retries after a few failures, then waiting before trying again. This prevents adding extra stress to an already overloaded system.
Example: If your application is experiencing high traffic and your test script fails to interact with the UI due to system strain, the Circuit Breaker will stop additional retries temporarily, reducing the load on the system and giving it time to recover.
2. Preventing Overly Aggressive Retrying
Scenario: In continuous integration/continuous deployment (CI/CD) pipelines, tests might experience temporary failures. The Circuit Breaker pattern stops a test from repeatedly retrying in such cases, avoiding unnecessary strain on the service.
Example: If your automated test fails due to a transient issue like a temporary network problem, the Circuit Breaker pattern will prevent excessive retries, which helps maintain test stability and avoids putting additional load on your network resources.
Benefits of the Circuit Breaker Pattern
- Prevents System Overload: By stopping retries after a certain number of failures, the Circuit Breaker pattern avoids overwhelming the system and provides it with time to recover.
- Improves Test Reliability: It prevents endless retries when failures are persistent, leading to more stable and reliable test outcomes.
- Efficient Resource Usage: It manages retry attempts in a controlled manner, reducing unnecessary load and conserving system resources.
- Better Failure Management: The pattern offers a structured approach to handle failures, minimizing the risk of retries making the situation worse.
- Enhanced Recovery: The cooldown period allows systems and services to recover before new retries are attempted, increasing the likelihood of successful future attempts.
Conclusion
Incorporating the Circuit Breaker pattern into your testing strategy can significantly enhance the stability and reliability of your tests. It helps manage intermittent failures more effectively and prevents system overload, making your test automation practices more robust and efficient.
