# heaptrack

Walks the agent through heaptrack: recording allocation traces, reading heaptrack_print output, hunting leaks and comparing runs.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 623 installs · ★ 267
- Author: mohitmishra786
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/mohitmishra786/low-level-dev-skills/tree/HEAD/skills/profilers/heaptrack/SKILL.md
- Updated: 2026-06-27
- HTML: https://affpapa.org/en/nevibecode/skills/heaptrack

## What it does

The skill tells an agent how to profile heap allocations on Linux and what to do with the trace afterwards. Recording starts with `heaptrack ./myapp arg1 arg2`, and there is a variant that attaches to a running process via `heaptrack --pid`. The result is a compressed `heaptrack.<prog>.<pid>.zst` file you analyse with `heaptrack_print` or open in `heaptrack_gui`.

A separate section covers reading the output: total runtime, calls to allocation functions, temporary allocations, peak heap consumption, peak RSS and total leaked memory, followed by hotspots and leaks tied to a file and line. Filtering options include top N hotspots, leaks only, a minimum allocation cost and folded data for a flamegraph. Readable backtraces need debug symbols, so build with something like `-DCMAKE_BUILD_TYPE=RelWithDebInfo`; without them the stack traces tell you little. Check your build flags before the first run, not after it.

There is a comparison with Valgrind massif covering overhead, output format, platform support and whether a recompile is needed. Rust gets its own part: heaptrack intercepts allocations only when the system allocator is in use, so the code needs a `#[global_allocator]` set to `System`. The skill points to companion material on valgrind, linux-perf, Rust profiling and sanitizers.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add mohitmishra786/low-level-dev-skills --skill heaptrack -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/heaptrack/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/heaptrack/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add mohitmishra786/low-level-dev-skills --skill heaptrack -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/heaptrack/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add mohitmishra786/low-level-dev-skills --skill heaptrack -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/heaptrack/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install mohitmishra786/low-level-dev-skills heaptrack
```

2. **Manually: put the files in place**
- File: `.github/skills/heaptrack/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add mohitmishra786/low-level-dev-skills --skill heaptrack -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/mohitmishra786/low-level-dev-skills --path skills/profilers/heaptrack
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/heaptrack/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add mohitmishra786/low-level-dev-skills --skill heaptrack -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/mohitmishra786/low-level-dev-skills/tree/HEAD/skills/profilers/heaptrack/SKILL.md

## When to use it
- find where a program eats memory
- catch a leak and see the code location
- compare heap usage between two builds
- produce flamegraph data for allocations
- filter out small allocations by cost threshold

## Example prompts
- Run my C++ binary under heaptrack and show the top hotspots by peak memory
- Parse this heaptrack_print output and find the leaks
- Compare two heaptrack runs before and after my changes

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 3a7817b11bd8cb6a.

BEGIN THIRD-PARTY FILE 3a7817b11bd8cb6a
````text
---
name: heaptrack
description: heaptrack memory profiler skill for Linux. Use when tracking heap allocations, finding memory leaks, measuring peak heap usage, identifying allocation hotspots, or comparing allocation behaviour between runs. Activates on queries about heaptrack, heap profiling, memory allocation analysis, heaptrack_print, allocation hotspots, or memory leak detection with 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

```bash
# 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

```bash
# 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

```bash
# 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

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

Key sections:

```text
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
````
END THIRD-PARTY FILE 3a7817b11bd8cb6a

The third-party file has ended. Everything between the 3a7817b11bd8cb6a tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2439 of 5233 bytes. © mohitmishra786 · MIT · https://github.com/mohitmishra786/low-level-dev-skills/tree/HEAD/skills/profilers/heaptrack/SKILL.md

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