🧠 C++ Memory Tracker

A Runtime Memory Leak Detection Tool Built from First Principles

Understanding memory is more important than memorizing tools.

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📌 Overview

Memory Tracker is a lightweight C++ runtime tool that detects memory leaks and incorrect deallocations by intercepting global dynamic memory operations (new, delete, new[], delete[]).

Instead of relying on external debuggers like Valgrind, this project focuses on building the core mechanism from scratch to deeply understand how memory tracking tools work at runtime.

The implementation is intentionally low-level, explicit, and transparent, emphasizing correctness and runtime behavior over abstraction.

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🎯 Why This Project Matters

Most C++ projects use memory debugging tools.
This project builds one.

It demonstrates:

• A clear understanding of the heap allocation lifecycle
• Correct global operator overloading in modern C++
• Handling of subtle runtime pitfalls (recursion, STL self-allocation)
• A systems-level debugging mindset

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✨ Features

• Intercepts all global dynamic allocations
• Tracks allocation metadata at runtime:
  • address
  • size
  • allocation type (new vs new[])
• Detects:
  • memory leaks
  • mismatched deallocations
  • invalid / double deletes
• Automatically prints a memory report at program exit
• Clean separation between interface (.h) and implementation (.cpp)

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🧠 Design Highlights

1. Global new / delete Interception

The tracker overrides all global allocation and deallocation operators, ensuring complete coverage of heap usage.

2. Malloc-based Internal Storage

To avoid infinite recursion caused by STL containers allocating memory internally, the tracker uses:

• a custom malloc-based allocator
• a thread_local re-entrancy guard

This prevents the tracker from tracking its own allocations.

3. Safe Shutdown Reporting

Memory reports are printed using C-style I/O (fprintf) instead of std::cout to avoid undefined behavior during static destruction.

This mirrors how real-world runtime tools are implemented.

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🛠 Build & Run

Compile

g++ -std=c++17 -O0 -Iinclude src/memory_tracker.cpp examples/leak_demo.cpp -o demo
 Run ./demo

Sample Output

Total allocations : 3 Total frees : 2 Bytes allocated : 48 Bytes freed : 44

MEMORY LEAKS DETECTED Leaked block at 0x55c8f2a3c2a0 of size 4 bytes

Non-Obvious Challenges Solved

-This project explicitly handles several advanced C++ pitfalls: -Sized delete overloads introduced in C++14 -Infinite recursion in global operator overloading -STL self-allocation during tracking -Unsafe I/O during program teardown

Author

Mohit Gunani IIT BHU