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Infosys·Software Engineer·Technical Phone Screen·Junior

Junior
May 2026

Summary

Interviewed for a SWE role at Infosys and got a fairly standard CS fundamentals question about garbage collection. Nothing too wild, but it made me realize how rusty I was on the internals.

Questions Asked (1)

Q1

Can you explain how garbage collection works in programming?

Technical Trade-offsSystem Design
Author's notes

I knew the basics but fumbled when they pushed on specific algorithms like mark-and-sweep vs reference counting.

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AI HintsAI Generated

Suggested Approach

Start by defining garbage collection as automatic memory reclamation, then explain the core algorithms (reference counting, mark-and-sweep, generational) and how they trade off throughput, pause times, and memory overhead. Finally, connect it to real-world impact in languages like Java or Python, and discuss how you'd tune or choose a GC strategy for a system.

Pro tip: Mention that understanding GC is crucial for diagnosing production issues like memory leaks and latency spikes, and that you've used tools like GC logs or profilers to optimize performance. This shows hands-on experience beyond textbook knowledge.

1. Define Garbage Collection

Explain that GC automatically reclaims memory occupied by objects no longer in use, preventing manual memory management errors like leaks and dangling pointers.

2. Describe Core Algorithms

Outline key techniques: reference counting (simple but cycle-prone), mark-and-sweep (traces reachable objects), and generational (exploits object lifetimes) with brief pros and cons.

3. Discuss Trade-offs

Highlight trade-offs: throughput vs. pause times, memory overhead vs. collection frequency, and how different collectors (e.g., G1, CMS) target specific goals.

4. Relate to Languages and Systems

Give examples: Java's JVM GC, Python's reference counting + cycle detector, Go's concurrent collector, and how each affects application design.

5. Conclude with Practical Impact

Summarize that GC choice impacts performance, scalability, and reliability, and mention tools (GC logs, profilers) for monitoring and tuning.

Key Points to Mention

  • Reference counting vs. tracing collectors
  • Mark-and-sweep and generational hypothesis
  • Stop-the-world pauses and concurrent collection
  • Memory leaks despite GC (e.g., unintentional object retention)
  • GC tuning parameters and their effects
  • Real-world examples: Java, Python, Go, C#

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.