Performance Testing Interview Questions and Answers
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📘 BASIC LEVEL QUESTIONS & ANSWERS
1. What is Performance Testing?
Performance Testing is a type of non-functional testing used to determine how a system performs in terms of responsiveness and stability under a particular workload.
2. What are the types of Performance Testing?
Load Testing
Stress Testing
Spike Testing
Endurance Testing
Volume Testing
Scalability Testing
3. Difference: Load, Stress, Spike Testing
Load Testing: Tests system behavior under expected load.
Stress Testing: Tests system behavior under extreme load.
Spike Testing: Tests response to sudden increase or decrease in load.
4. What tools have you used?
JMeter, LoadRunner, NeoLoad, Gatling, BlazeMeter, Locust.
5. Performance Testing Life Cycle
Requirements Gathering → Test Planning → Environment Setup → Script Creation → Test Execution → Monitoring → Analysis → Reporting.
6. What are performance bottlenecks?
Issues like CPU, Memory, Network, or Disk I/O limitations causing performance degradation.
7. What is Throughput?
Amount of data transferred in a given time. Measured in requests/sec or KB/sec.
8. Latency vs Response Time
Latency: Delay before the response starts.
Response Time: Total time from request to response.
9. Determining User Load
Based on production data, expected concurrent users, business use cases, and SLAs.
10. Ramp-up and Ramp-down
Ramp-up: Gradual increase in user load.
Ramp-down: Gradual decrease of the load after test.
11. Think Time and Pacing
Think Time: Pause between user actions.
Pacing: Time between iterations.
12. Performance Metrics
Response Time, Throughput, Hits/sec, Error Rate, CPU/Memory Utilization.
13. Challenges in Performance Testing
Environment setup, test data, simulating real user behavior, interpreting results.
14. How to Analyze Results
Use graphs, response time trends, error logs, compare against baseline and SLA.
15. Role of Test Script
Automates user actions, simulates load, supports parameterization and correlation.
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📗 ADVANCED LEVEL QUESTIONS & ANSWERS
1. Identifying Bottlenecks using APM
Use tools like AppDynamics, Dynatrace to monitor real-time metrics (CPU, Memory, Thread count, DB queries) to pinpoint slow components.
2. Correlation in JMeter/LoadRunner
Dynamic values (like session IDs) are extracted using Regular Expressions or correlation functions to maintain session integrity.
3. Parameterization
Replacing hardcoded values (like usernames) with variables to simulate real user behavior.
4. Endurance Testing
Long-duration test to identify memory leaks, database connection issues, and degradation.
5. Workload Modeling
Based on usage data: peak hours, transaction mix, user patterns. Determines how virtual users behave.
6. Monolithic vs Microservices Testing
Monolithic: Single app, end-to-end testing.
Microservices: Multiple APIs, requires individual and integrated testing with mocking.
7. Role of APM Tools
Provides end-to-end traceability, identifies root causes, tracks SLAs, provides dashboards.
8. Garbage Collection Impact
Frequent
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