heaptrack

heaptrack

Purpose

Guide agents through heaptrack for heap allocation profiling on Linux: recording allocation traces, analysing with heaptrack_print, identifying leaks and hotspots, and comparing runs.

Triggers

• "How do I find memory allocation hotspots in my C++ program?"
• "My program uses too much memory — how do I find where?"
• "How do I use heaptrack to detect memory leaks?"
• "What is heaptrack and how does it differ from Valgrind massif?"
• "How do I compare memory usage between two program versions?"
• "heaptrack_print output — how do I interpret it?"

Workflow

1. Installation

# Ubuntu/Debian
sudo apt-get install heaptrack heaptrack-gui

# Fedora
sudo dnf install heaptrack

# Arch
sudo pacman -S heaptrack

# Build from source
git clone https://github.com/KDE/heaptrack.git
cmake -S heaptrack -B heaptrack-build -DCMAKE_BUILD_TYPE=Release
cmake --build heaptrack-build -j$(nproc)

2. Basic usage

# Profile a program (generates heaptrack.<prog>.<pid>.zst)
heaptrack ./myapp arg1 arg2

# Attach to running process
heaptrack --pid 12345

# Analyse the trace file
heaptrack_print heaptrack.myapp.12345.zst

# GUI analysis (if heaptrack-gui installed)
heaptrack_gui heaptrack.myapp.12345.zst

3. Build for better profiling

# Build with debug symbols (essential for readable backtraces)
cmake -S . -B build -DCMAKE_BUILD_TYPE=RelWithDebInfo
cmake --build build

# Then profile
heaptrack ./build/myapp

4. Interpreting heaptrack_print output

heaptrack_print heaptrack.myapp.*.zst 2>/dev/null

Key sections:

total runtime: 2.34s
calls to allocation functions: 145,234 (62,064/s)
temporary allocations: 89,123 (38,087/s)
peak heap memory consumption: 45.23MB
peak RSS (including heap): 78.45MB
total memory leaked: 2.34MB

# Top allocation hotspots (by peak memory)
hotspot 1: 12.34MB peak
  myapp::cache::Cache::insert(...)
    at src/cache.cpp:142
  ...

# Top leaked allocations
leak 1: 2.34MB leaked in 1,234 allocations
  myapp::connection::Connection::new(...)
    at src/connection.cpp:67