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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
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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
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What will happen if my site
hits the reddit front page?
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What if reddit doesn’t matter to me?
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Prove how many users can access
your site at one time.
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Load Testing or Stress Testing?
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Load Tests: Will my site run well with
the expected amount of users?
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Stress Tests: How many users before
the site/infrastructure cracks?
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Are we testing dynamic or cached requests?
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INTERNET
PHP
FRONT-END CACHE
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Varnish/Static: ~50ms
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PHP: ~100ms
(without stress)
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PHP: ~1500ms
(with stress)
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All methods are not equal.
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“Users/minute” does not necessarily
mean “real users during a minute”.
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There are many utilities for stress testing.
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Let’s start with Siege.
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You can run cached or dynamic tests.
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It’s used only from the command line.
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It only runs tests from one server.
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Linux: Packages.
Mac: Homebrew.
https://www.joedog.org/siege-‐home/
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Primary configuration (.siegerc)
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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
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A list of URLs.
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List format
HOST=http://example.com
${HOST}/
${HOST}/?feed=rss2
${HOST}/?p=41
${HOST}/?feed=rss2
${HOST}/?p=44
${HOST}/
...
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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
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Where can I find test content?
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HHVM’s oss-performance is one option.
https://github.com/hhvm/oss-‐performance/tree/master/targets/wordpress
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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}
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You can also use sproxy,
not to be confused with stunnel.
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Loader.io is a service to run stress tests.
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However, it has a friendly GUI to run
tests and see the results.
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No content
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Single data center, but from a
cluster of AWS servers.
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More complex user behavior?
Try a service like LoadStorm.
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What kinds of issues will I find?
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How do I debug problems once
they’re found?
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Bonus: Your WordPress site runs slowly,
and even more slowly as soon as you
enable a persistent object-cache.
Why?
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alloptions.
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Memcached slab size.
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wp_options cleanup.
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Questions?
-‐
getsource.net/tag/siege/
-‐
joedog.org/siege-‐manual/
-‐
joedog.org/sproxy-‐home/
-‐
github.com/hhvm/oss-‐performance
Mike Schroder (DH-Shredder)
WordPress Platform Lead at DreamHost
@GetSource - http://www.getsource.net