Legen... [Not] wait for it... dary!!! Legendary
How to shorten the time of waiting for your application to load and respond
Hello, speedsters!
Since it began, I’m a big fan of How I met your mother. But in everything related to waiting I don’t have the patience, neither your users.
In the past, I was usually trying to fine-tune the code of my application, either by coding better or using the most performant tools and techniques. But in several recent jobs, I've noticed that the performance issue was not actually in the code but was "around" the application.
For example:
Timeouts between the printer at the locations and my server - in the APM, the request processing time takes tens of milliseconds, so why a timeout?
Long query time to database - but the query was optimized and ran a few milliseconds on the query client when tested.
The issue was high latency between the client and the server because of a nonoptimal geolocation deployment of servers.
For example, the database deployed in the west region while the application server was in the east region. In another case I had, the app servers and the database were on two different continents (Europe and the U.S.)
Nowadays, this issue is too common because provisioning servers is so easy, trying to keep cloud costs cheap and the separation between developers and the cloud infrastructure maintainers.
Let's demonstrate the issue by exploring the latency difference between a few countries. We will use https://wondernetwork.com/pings, one of the greatest sites I found a couple of years ago, telling the story of the importance of latency.
The website runs about 30 pings and shows the average; a ping is the time for the round trip between the sender and receiver (Client ↔ Server).
So, to establish the first TCP connection between a client and a server (Browser and Application Server, App Server and DB, etc.) - it takes ping-time X 1.5 to pass the 3-Way handshake.
Then, each transferring of packet of data will take the ping time. A standard TCP packet is up to 1.5KB, so to pass 15KB of data, you wait for at least a ping-time X 10 packets if none of the packets dropped in the middle.
Now imagine how long it takes to pass 100 records of shop listings with their full catalog and item descriptions between an app server in Europe and a database server in the U.S. Or how long it takes the browser to download your single-page application from your servers.
There are many ways to decrease the latency of your app, to name a few:
Manually align the deployment of your servers in the same region on your cloud provider
Working with private networks inside your cloud provider
Using a CDN for static content
Keeping connections alive between sender and receiver
There are many more ways to decrease the latency of your app, which I will elaborate on in the following posts in the latency series.
If you liked the post, please share it with your friends and help me reach a bigger audience so we will not have to wait the next time we use any app to load ;)