Amazon Interview Question
SDE-2sCountry: United States
Interview Type: In-Person
Internal reasons (server side system issues):
1. I/O
2. CPU
3. Memory
4. Network
5. Storage
Application related (require to test applications algorithms):
1. Skewed load-balancing algorithm
2. Database query optimizations
External issues (client-related):
1. Festive season
2. Cash crunch (just when India banned black money)
3. newly added products are the ones most popular at competitive pricing (so again increased traffic).
Internal issues need to be tested first with some performance monitoring tools for all 5 factors and then application related issues and then client-related.
If you can ask questions, surely you should get more info on it.
They said " In the past 24 hours processing the customer order is taking really long time".
I would firstly ask what do they mean by "processing". Does it mean
- submitting order by customer on website
- getting placed order to warehouse delivery system
- getting product from warehouse to delivery team
- maybe delivering to customer, etc
In other words narrow down where the bottleneck can be.
Also is it experienced by all customers? If not, then by which? Maybe new customers, or maybe customers from specific country, or maybe customers which used specific payment way - ex paypal, or visa, or specific system or browser, or maybe only regular or prime customers?
Is this delay experienced on all goods? or only certain products?
Does nagios (or any of their network monitoring system) reports any faults?
Also product which were added in last 24 hours, was it excessive (unusual) amount of products add?
Did they have similar problem before, and if so, what was the reason?
I could go on and on...
I don't know how all of you missed this point since the new products are added, means the cache is not warm and all the queries pertaining to the new product are hitting the database now. This will result in increased load on DB operations.
Hence more DB queries, slower data replication, and hence slower system.
1) Check if traffic has increased. Is it normal/expected increase (say Diwali festival season) or unexpected. If it it is unexpected then analyze further if there is any suspicious from particular geographical area, phishing attack etc.
- Kaushik Lele October 30, 20162) Check Server performance; any application server crashes ; memory issues observed
3) Check Database performance; DB server outage; memory issue;network connectivit issue.
If particular operation is taking long time to process then need to fine tune queries.
4) Overall network performance. Any outage; increased latency etc.