scaling quizlet

Scaling Quizlet

Andrew SutherlandFounder

Friday, April 20, 12

Quizlet.com

We provide educational tools for millions of kids.

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• 70M pageviews/mo

• 7.5M uniques/mo

• Quantcast US Rank: #385

• 99.97% uptime this year

Traffic

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Traffic Pattern

6x growth in 4 weeks, every yearFriday, April 20, 12

• 160 GB in MySQL

• 1.1B rows in `answers` table

• One big 48GB master does it all (are we crazy?)

Data

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• 2 Load Balancers

• 3 Web Servers

• 2 Database machines

• ~15 machines doing services

Architecture

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Page requests: - 750 rps peak - 300 rps avg

Memcached: - 2,500 qps peak - 1,000 qps avg

MySQL:- 1,100 qps peak- 465 qps avg

Throughput

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Removing joins.

Putting all ID-based lookups in memcached.

3x’d our performance overnight,prevented complicated architecture

Biggest single win(2010)

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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().

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Need better visibility into apps

Site got 2x faster here

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AVERAGESSUCK

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Enter New Relic(live demo)

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New Relic isn’t enough.

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Check out our super-crappy,super-awesome Inline I/O viewer

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And our super-crappy,super-awesome App log viewer

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Check out our super-crappy,super-awesome Log Viewer

Our log viewer

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YOUR LOGSARE

RELATIONALFriday, April 20, 12

• User ID• IP address• Type• Frequency• Type+Frequency• Response times

Log lookups by

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Scalable diagnosis of user issues with

feedback(demo)

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We built a game in Node.

It rocks.

The Future

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We built a game in Node.

It rocks.

Future

Friday, April 20, 12

We built a game in Node.

It rocks.

Future

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Single user might have 5 messageswith the server in 1 second.

Connection lasts 30 minutes,not 100ms.

New Scaling Story

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We’re exploring this now.And need help.

Scaling node

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Random Tips

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http://showmewhatswrong.com/

Show Me What’s Wrong

Second coolest website ever.

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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.

Poor man’s SMS alerts

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Get the New Relic Menu BarAlways know about how much traffic you have.

Ambient Traffic Awareness

(Available in Mac App Store)

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Use Vogue!

Never refresh for CSS again!

Voguegithub.com/quizlet/vogue

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Thanks!

Follow:@asuth

@quizlet

Friday, April 20, 12