AtomicBank

I wish it'd be that simple for my money

Performance

The checks were made with k6 and pprof. k6 results:

Metric	Value	Interpretation
Peak Throughput	5,000 RPS	API capacity
Total Requests	170,292	Processed during the 1m test
Success Rate	99.86%	Reliability under stress
Median Latency	3.14 ms	Rsponse under normal load
Lock Contention	1,500 RPS	Write-rate for a single row

pprof results:

Resource	Value	Profile Analysis
Memory (Heap)	~46.2 MB	Efficient memory management and GC
Top Allocator	bufio (35%)	Most memory spent on I/O buffering
DB Driver	pgx (28%)	Stable connection pooling (pgxpool)
Concurrency	2,527 VUs	Lightweight goroutines for parallel tasks

Thoughts

• I'm assuming this service is made for financial txs where its important not to lose data
• Error messages can be imporoved
• Logs're just for console, they should be tunned to write to files
• Some security checks were skipped on purpose. Security can be improved

Integration and load tests

Running basic isolated tests for all logic:

go test -v ./internal/transport/...

Running load tests:

1. install k6 first: https://grafana.com/docs/k6/latest/set-up/install-k6/
2. lift the image:

docker compose up --build

3. run tests:

k6 run .\testing\load_test.js

Manual testing

Assuming you didn't change the default port (5000) from .env.example

Check if this crap works. Should return timestamp:

GET http://localhost:5000/api/v1/ping

---

Create new wallet (new for each request):

POST http://localhost:5000/api/v1/wallet/new

Response:

{
  "id": "c07a5615-10a7-4774-bced-d45474cb1702",
  "balance": 0
}

---

Get wallet balance:

GET http://localhost:5000/api/v1/wallets/{UUID}

Response is just a raw balance:

300

---

Make transaction

POST http://localhost:5000/api/v1/wallet

Payload:

{
  "walletId": "c07a5615-10a7-4774-bced-d45474cb1702",
  "operationType": "deposit", // Or "withdraw"
  "amount": 10
}

Response is ok or error message:

ok