Ruby on Rails Research & Evidence-Based Practice 3

Question 1

Which gem is the de facto standard for load testing Rails endpoints to gather quantitative throughput evidence?

Accepted Answer

Siege or wrk (external tools)

Answer

External tools like `siege` or `wrk` generate HTTP load against a Rails server and report requests/sec and error rates.

Question 2

In Rails, `ActiveSupport::Notifications` can be subscribed to for performance research. Which event reports SQL query timing?

Accepted Answer

sql.active_record

Answer

The `sql.active_record` event is published by ActiveRecord for every SQL execution and includes duration, allowing custom metrics collection.

Question 3

A developer wants peer-reviewed evidence before choosing between Redis and Memcached for Rails caching. What is the most rigorous evaluation approach?

Accepted Answer

Benchmark both with the app's actual access patterns and data sizes

Answer

Evidence-based decisions require benchmarks against the specific workload, not generic benchmarks or popularity metrics.

Question 4

Which Rails configuration setting must be enabled to collect Rack middleware timing data as evidence for response time analysis?

Accepted Answer

config.middleware.use Rack::Runtime

Answer

`Rack::Runtime` adds an `X-Runtime` header to responses containing the total request processing time in seconds.

Question 5

To establish whether a database index improves query performance, a developer should compare execution plans before and after. Which PostgreSQL keyword in Rails' `explain` output confirms an index is being used?

Accepted Answer

Index Scan

Answer

`Index Scan` in a PostgreSQL EXPLAIN output confirms the query planner is using an index rather than a sequential scan.

Ruby on Rails Practice Test

Ruby on Rails Practice Test

Ruby on Rails Research & Evidence-Based Practice 3