Lesson 3

Why stateless servers?

Break it

At second 10, app-2 goes down. Turn traffic up to 1,200 requests per second.

Users

600 req/s

Load balancer

splits evenly

1%

App servers

× 2 · 1 down

63%

Cache

Not added

Off

DB primary

reads + writes

42%

Read replicas

None

Off

Traffic600 req/s

p50 latency

131 ms

Failed requests

0.0%

Monthly cost

$220

Users logged out

5,000

What happened during the run

Second 10: app-2 went down. 5,000 users were logged out.