1. Scaling Quizlet
Andrew Sutherland
Founder
Friday, April 20, 12

2. Quizlet.com
We provide educational tools for millions of kids.
Friday, April 20, 12

3. Traffic
• 70M pageviews/mo
• 7.5M uniques/mo
• Quantcast US Rank: #385
• 99.97% uptime this year
Friday, April 20, 12

4. Traffic Pattern
6x growth in 4 weeks, every year
Friday, April 20, 12

5. Data
• 160 GB in MySQL
• 1.1B rows in `answers` table
• One big 48GB master does it all
(are we crazy?)
Friday, April 20, 12

6. Architecture
• 2 Load Balancers
• 3 Web Servers
• 2 Database machines
• ~15 machines doing services
Friday, April 20, 12

7. Throughput
Page requests:
- 750 rps peak
- 300 rps avg
Memcached: MySQL:
- 2,500 qps peak - 1,100 qps peak
- 1,000 qps avg - 465 qps avg
Friday, April 20, 12

8. Biggest single win
(2010)
Removing joins.
Putting all ID-based lookups in
memcached.
3x’d our performance overnight,
prevented complicated architecture
Friday, April 20, 12

9. Watching syscalls with
DTrace
dtrace -n 'syscall::open:entry { printf("%s
%s",execname,copyinstr(arg0)); }'
Found PHP opening files because of
require_once(). Switched to require().
Friday, April 20, 12

10. Need better visibility
into apps
Site got
2x faster
here
Friday, April 20, 12

11. AVERAGES
SUCK
Friday, April 20, 12

12. Enter New Relic
(live demo)
Friday, April 20, 12

13. New Relic isn’t enough.
Friday, April 20, 12

14. Check out our super-crappy,
super-awesome Inline I/O viewer
Friday, April 20, 12

15. And our super-crappy,
super-awesome App log viewer
Friday, April 20, 12

16. Our log viewer
Check out our super-crappy,
super-awesome Log Viewer
Friday, April 20, 12

17. YOUR LOGS
ARE
RELATIONAL
Friday, April 20, 12

18. Log lookups by
• User ID
• IP address
• Type
• Frequency
• Type+Frequency
• Response times
Friday, April 20, 12

19. Scalable diagnosis of
user issues with
feedback
(demo)
Friday, April 20, 12

20. The Future
We built a game in Node.
It rocks.
Friday, April 20, 12

21. Future
We built a game in Node.
It rocks.
Friday, April 20, 12

22. Future
We built a game in Node.
It rocks.
Friday, April 20, 12

23. New Scaling Story
Single user might have 5 messages
with the server in 1 second.
Connection lasts 30 minutes,
not 100ms.
Friday, April 20, 12

24. Scaling node
We’re exploring this now.
And need help.
Friday, April 20, 12

25. Random Tips
Friday, April 20, 12

26. Show Me What’s Wrong
Second coolest website ever.
http://showmewhatswrong.com/
Friday, April 20, 12

27. Poor man’s SMS alerts
Setup GMail filter for SMS
1. Add filter for name+sms@hotstartup.com
2. Forward to 4155551234@vtext.com (VZW)
3. Your app can now text you anytime, for free.
Friday, April 20, 12

28. Ambient Traffic
Awareness
Get the New Relic Menu Bar
Always know about how much traffic you have.
(Available in Mac App Store)
Friday, April 20, 12

29. Use Vogue!
Never refresh for CSS again!
Vogue
github.com/quizlet/vogue
Friday, April 20, 12

30. Thanks!
Follow:
@asuth
@quizlet
Friday, April 20, 12