Scout APM

What is APM?

Application Performance Monitoring (APM), as the name suggests, is the process of monitoring the performance of the many aspects of your application (i.e., CPU processors, memory, storage of machines that host your web servers, APIs, databases, file systems, etc.).

Common Use Cases for APMs

Application Development
Identifying Performance Bottlenecks
Real-time Performance Alerts and Insights
Monitor and Track End User Experience
Cost optimisation

Getting started with Scout

Response Time - MEAN

Average response time for a selected time frame(74.2).

Response Time - 95th

95% of request responses are below this value(127.6). Also, one more thing to take note of is this value should not exceed Mean response time * 4X (74.2*4 = 296.8)

Throughput

Total number of requests per minute for a selected time frame

Errors

404, 500 errors happened during the selected time frame

Memory

Memory usage of the application

APDEX

Apdex is a measurement of a user’s level of satisfaction based on the response time of request(s) when interacting with the application. 0-1 (0 being unsatisfactory and 1 being satisfactory).

What to look into Scout?

N+1 Insights

When we talk about the N+1 problem, what we are describing is the inefficient way of querying data from the database, resulting in an unnecessary amount of individual SQL queries being executed. A small inefficiency like this will often go unnoticed in development, but then suddenly cripple the application’s performance when deployed to production.

Reference - https://scoutapm.com/blog/finding-and-fixing-n1-queries

More information - https://app.weet.co/play/0688e50a/weet-free-video-messaging

Slow query Insights

Once your Rails app begins seeing consistent traffic, slow SQL queries will likely rear their ugly head. While PostgreSQL can log slow queries, it’s difficult to get actionable information from this raw stream. The slow query logs lack application context.

Possible solutions - indexes

Reference - https://scoutapm.com/blog/finding-slow-activerecord-queries-with-scout, https://use-the-index-luke.com/

More information - https://app.weet.co/play/5718938d/weet-free-video-messaging

Memory bloat Insights

Memory bloat is caused by loading too much into memory, usually as a result of poor memory management in the software, for example – when you load lots of unnecessary data objects into memory that are neither utilized by the application nor released from memory. Nowadays, with growing audiences and faster speed and data retrieval expectations, memory issues pose a huge threat to performance and can lead to huge losses in terms of customers and money.

Possible solutions - Jemalloc, Frozen string literals

Reference - https://scoutapm.com/blog/memory-bloat , https://scoutapm.com/blog/manage-ruby-memory-usage, https://www.mikeperham.com/2018/04/25/taming-rails-memory-bloat/, https://freelancing-gods.com/2017/07/27/an-introduction-to-frozen-string-literals.html, https://freelancing-gods.com/2017/07/27/friendly-frozen-string-literals.html

Errors

Errors happening in the application. we can also integrate error tracking tools like rollbar, and sentry into scout.