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Siege and Beyond:
 An Intro to Benchmarking and Stress Tests

Siege and Beyond:
 An Intro to Benchmarking and Stress Tests

Benchmarking is an important practice for high-traffic sites, or even low traffic sites that may have high-traffic spikes.

What will happen to your site if it hits the Reddit front page? Without benchmarking and stress testing, there’s no good way to know how your site will perform under true load.

In this session, you’ll learn some of the basics of benchmarking, some good tools to get started, and when stress tests are the right tool for your site’s performance concerns. Finally, you’ll learn some common performance problems found through stress tests, and their solutions.

Presented at WordCamp Vancouver 2015 by Michael Schroder


Mike Schroder

August 15, 2015

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  1. Siege and Beyond:
 An Intro to Benchmarking and Stress Tests

    WordCamp Vancouver 2015 Mike Schroder (DH-Shredder) WordPress Platform Lead at DreamHost @GetSource - http://www.getsource.net
  2. Who Am I? • Mike Schroder, a.k.a DH-Shredder,
 a.k.a. @GetSource

    • Third Culture Kid, enjoy Coffee & Sailing • WordPress 3.9 Co-Lead and Core Contributor • Happy DreamHost Employee
  3. What will happen if my site hits the reddit front

  4. What if reddit doesn’t matter to me?

  5. Prove how many users can access your site at one

  6. Load Testing or Stress Testing?

  7. Load Tests: Will my site run well with the expected

    amount of users?
  8. Stress Tests: How many users before the site/infrastructure cracks?

  9. Are we testing dynamic or cached requests?


  11. Varnish/Static: ~50ms

  12. PHP: ~100ms (without stress)

  13. PHP: ~1500ms (with stress)

  14. All methods are not equal.

  15. “Users/minute” does not necessarily mean “real users during a minute”.

  16. There are many utilities for stress testing.

  17. Let’s start with Siege.

  18. You can run cached or dynamic tests.

  19. It’s used only from the command line.

  20. It only runs tests from one server.

  21. Linux: Packages.
 Mac: Homebrew. https://www.joedog.org/siege-­‐home/

  22. Primary configuration (.siegerc)

  23. To run dynamic tests login-url = http://example.com/wp-login.php POST log=[user]&pwd=[password]&wp-submit=Log+In& redirect_to=http%3A%2F%2example.com%2Fwp-admin%2F&testcookie=1

  24. A list of URLs.

  25. List format HOST=http://example.com ${HOST}/ ${HOST}/?feed=rss2 ${HOST}/?p=41 ${HOST}/?feed=rss2 ${HOST}/?p=44 ${HOST}/ ...

  26. Results Transactions: 712 hits Availability: 100.00 % Elapsed time: 59.12

    secs Data transferred: 3.70 MB Response time: 1.23 secs Transaction rate: 12.04 trans/sec Throughput: 0.06 MB/sec Concurrency: 14.75 Successful transactions: 702 Failed transactions: 0 Longest transaction: 8.49 Shortest transaction: 0.20
  27. Where can I find test content?

  28. HHVM’s oss-performance is one option. https://github.com/hhvm/oss-­‐performance/tree/master/targets/wordpress

  29. To seed from your own content, take a look at

    your logs, or try: http://example.com/   http://example.com/?feed=rss2   http://example.com/?p=%{*:1-­‐52}  
  30. You can also use sproxy, not to be confused with

  31. Loader.io is a service to run stress tests.

  32. However, it has a friendly GUI to run tests and

    see the results.
  33. None
  34. Single data center, but from a cluster of AWS servers.

  35. More complex user behavior? Try a service like LoadStorm.

  36. What kinds of issues will I find?

  37. How do I debug problems once they’re found?

  38. Bonus: Your WordPress site runs slowly, and even more slowly

    as soon as you enable a persistent object-cache. Why?
  39. alloptions.

  40. Memcached slab size.

  41. wp_options cleanup.

  42. Questions? -­‐    getsource.net/tag/siege/   -­‐    joedog.org/siege-­‐manual/   -­‐

 -­‐    github.com/hhvm/oss-­‐performance
 Mike Schroder (DH-Shredder) WordPress Platform Lead at DreamHost @GetSource - http://www.getsource.net