8. How we define Performance
• Response Time
The time it takes for an application to respond to a user request.
• Throughput
The amount of concurrently processed request in a given time period.
e.g.: requests/minute.
• Availability
Status of our systems. Are they up and running for us and our users?
• Accuracy
Is the response what the user actually expected? Are there any errors
10. Types of Measurement
• Cyclic Measurements
– Are collected ar regular time intervals
– Are time based
– JMX, CPU, Memory
• Event-based measurements
– Are collected as a request occurs
– Are transactional
– Response Times, CPU consumption
12. How can this happen?
A: Our response time is 2.3 seconds
B: Our response time is 1.5 seconds
C: Our response time is 6 seconds
13. Measurement Aggregation
• Minimum and Maximum
The best and the worst request. Beware of outliers.
• Average
Sum/Count. Uses in many cases. Quality depends on actual values.
• Median
What 50 percent of our users see.
• Percentile
What n percent of our users see.
16. Agree on Measurement Approach
Page Load Time HTTP Request Time 95 % Servlet Time
Network
Browser Firewall Sniffer Web Server Application
Server
Request Time (max)
23. How do we manage
performance and
solve problems?
24. Types of Problems
• Data-Driven Problems
Problems which occur for specific users, scenarios and which
depend on (input) parameters e.g.: a search query
• Load Driven Problems
Problems which depend on the current system load. Usually
occur at higher load. In most cases resource dependent. e.g.:
increased response time with more users.
• Environment Driven Problems
Problems caused by factors outside the application. e.g.:
hardware, network connectivity, etc.
25. Operations Main Tasks
• Monitoring
Collect all relevant KPIs and check against SLAs and
baselines?
• Alerting/Incident Management
Inform ops about problems
• Impact Analysis
Analyze the impact of issues. Who is affected?
• Isolation
What is the cause of a problem and who must I talk to?
• Diagnosis
Why is there a problem and how can we fix it?
26. Key Performance Indicators/Metrics
• Visitors and Requests
How many people are using our site?
• Response Times
How fast do we service requests.?
• Errors and Failed Transactions
How many problems do we see and how often do they affect
functionality?
• Availability
Can our systems currently be reached?
• Utilization Metrics
Do we have enough resources and are we using them
efficiently?