1. Optimization of web applications An introduction

3. Worked for 3 years as a Web Developer

4. Then 2.5 years as a Perl Programmer handling large scale ecommerce web sites

5. Then for 2.5 years as Software Architect, Team Lead for (J2EE)

7. Overview How does Apache Prefork handle your request Projects that #Failed What I have learned

8. Apache Prefork

9. Request/Response Cycle (Apache Prefork) Apache Main Process Request on port 80

10. Request/Response Cycle (Apache Prefork) Apache Main Process Request on port 80 ForkChild Child Process

11. Request/Response Cycle (Apache Prefork) Apache Main Process Apache Main Process Request on port 80 ForkChild Child Process SendRespond

12. Request/Response Cycle (Apache Prefork) Request/Response Cycle (Apache Prefork) Apache Main Process Apache Main Process Child Process Child Process

13. Request/Response Cycle (Apache Prefork) Apache Main Process Requeston port 80 Child Process

14. Request/Response Cycle (Apache Prefork) Apache Main Process Requeston port 80 Child Exists Child Process

15. Request/Response Cycle (Apache Prefork) Apache Main Process Apache Main Process Child Exists Child Process Child Process

16. Request/Response Cycle (Apache Prefork) Apache Main Process Child Process Child Process

17. Request/Response Cycle (Apache Prefork) Apache Main Process Child Process Child Process

18. Request/Response Cycle (Apache Prefork) Apache Main Process Child Process Child Process

19. Past Failings Conclusions Minimize response time Do not let the children hang Don’t use to many children

20. How I #Failed

21. Challenges : Component Failure # Failure Hardware failure RAID fails Node in cluster fails

22. Challenges : Component Failure # Failure Hardware failure RAID fails Node in cluster fails Learning : Design for 60% usage KISS

23. Challenges : Peaks in traffic # Failure Successful marketing campaigns Radio Station – 10 stations announcement TV Personality – News agency interviews

24. Challenges : Peaks in traffic # Failure Successful marketing campaigns Radio Station – 10 stations announcement TV Personality – News agency interviews Learning Try to stagger your communications Soft launch when you can

25. Challenges : Peaks in traffic # Failure Important news events

26. Challenges : Peaks in traffic # Failure Important news events Learning : Estimate your peak and design for it

27. Challenges : Unproven code # Failure Third party libraries can go wrong

28. Challenges : Unproven code # Failure Third party libraries can go wrong Learning Beware of 3rd party libraries Profile all new code Profile all new code Profile all new code

29. Challenges : Unproven code # Failure Updated System libraries Memcached client libraries update GD2 Client library update

30. Challenges : Unproven code # Failure Updated System libraries Memcached client libraries update GD2 Client library update Learning Beware when updating production servers Always have a Hot backup to rollback

31. Challenges : Stress tests # Failure Stress tests the false insurance

32. Challenges : Stress tests # Failure Stress tests the false insurance Learning Correct planning of test scenarios Correct estimation of your traffics shape Replicate a production environment as closely as possible

34. Understand your Software components

35. Understand your Human components

37. Optimization Optimization is not about code Optimization is not about RAIDed disks Optimization is not about software architecture Optimization is not about caching systems Optimization is not about load

38. Optimization Optimization is not about code Optimization is not about RAIDed disks Optimization is not about software architecture Optimization is not about caching systems Optimization is not about load Optimization is about all the pieces working in unison Optimization is an ongoing process

39. Optimization : Finding the bottleneck Optimization starts with Risk

40. Optimization : Finding the bottleneck Optimization starts with Risk Set the Assumptions # Users Mix of traffic Connection speed ....

41. Optimization : Finding the bottleneck Optimization starts with Risk Set the Assumptions # Users Mix of traffic Connection speed .... Define your System metrics Page load time Page weight Memory usage CPU Usage Load average

44. Profile the code

45. CPU Time

46. Look at %Optimization starts with Risk Set the Assumptions # Users Mix of traffic Connection speed .... Define your System metrics Page load time Page weight Memory usage CPU Usage Load average

48. Profile the code

49. CPU Time

50. Look at %

51. Load test your systemOptimization starts with Risk Set the Assumptions # Users Mix of traffic Connection speed .... Define your System metrics Page load time Page weight Memory usage CPU Usage Load average

53. Profile the code

54. CPU Time

55. Look at %

56. Load test your system

57. Tweak your system

58. Max Children

59. Spare Children

60. NFS settings

61. Caching

62. Session handling

63. Etc ...Optimization starts with Risk Set the Assumptions # Users Mix of traffic Connection speed .... Define your System metrics Page load time Page weight Memory usage CPU Usage Load average

64. Optimization : Finding the bottleneck Conclusion I am more riskconscious I think before I code I profile, and profile, and profile I define my test scenarios Development environment as close as possible to the Production environment I test my deployments And always have a Plan B in case I forget something!