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Q80: How Do You Test Concurrent API Requests?

🔀Core Concept

How Do You Test Concurrent API Requests?

Key Takeaways & Architecture Summary

✓Use load generators to fire multiple requests in the exact same millisecond.
✓Verify that transaction states remain consistent (ACID checks).
✓Expose race conditions, database thread pool exhaustion, and memory leaks.

Direct Answer Summary

Testing concurrency requires using load generation engines to fire multiple requests in the exact same millisecond. This evaluates how the backend handles parallel transactions, ensuring that database locks prevent race conditions, dirty reads, or thread pool exhaustion.

⚠️ Senior Engineering Warning (Red Flag)

Never think sequential requests simulate real concurrency. Sequential loops run one request after another; concurrent tests send requests in parallel, testing the server's thread-handling limits.

💡 STAR Architectural Explanation & Pro Tip

Concurrency testing exposes critical race conditions. For example, if two users attempt to reserve the same seat simultaneously, the API must handle locks correctly to prevent double bookings.

RestAssuredTest.java

Rest-Assured + Java

// Java thread-pool script executing concurrent API calls
ExecutorService service = Executors.newFixedThreadPool(10);
for (int i = 0; i < 10; i++) {
    service.submit(() -> {
        RestAssured.get("/api/v1/jobs");
    });
}
service.shutdown();