Explain Large Memory Allocation, Swap, and C++ Inline Trade-offs
Company: Hudson River Trading
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: hard
Interview Round: Technical Screen
In a low-level C++ interview, explain what happens when a program requests 8 GB of memory on a machine with 4 GB of RAM, and discuss the purpose and downsides of the `inline` keyword.
### Constraints & Assumptions
- Discuss virtual memory rather than assuming physical RAM is allocated immediately.
- Behavior depends on OS overcommit policy and whether memory is touched.
- Use C++ allocation terms carefully.
- Inline should cover both language/linkage and optimization aspects.
### Clarifying Questions to Ask
- Is the allocation through `malloc`, `new`, `mmap`, or a container?
- Which operating system should be assumed?
- Is swap enabled?
- Does the program touch all allocated pages?
- Are we discussing inline functions or inline variables?
### What a Strong Answer Covers
```premium-lock What a Strong Answer Covers
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### Follow-up Questions
- What changes if swap is disabled?
- What happens inside the page-fault handler?
- How does demand paging help?
- Why might inline hurt instruction-cache performance?
Quick Answer: This Hudson River Trading software engineering question probes large memory allocation, swap behavior, and C++ inline trade-offs. It prepares candidates to explain operating-system effects and language-level performance choices with the precision expected in systems interviews.