livecore

A low-pause, capture-only Linux core dumper written in Go.

Overview

livecore produces core files from running Linux processes with minimal stop-the-world (STW) time by using iterative pre-copy passes and a short final delta copy.

The motivation is to run goref against processes with hundreds of gigabytes of memory where grf attach PID is too slow and would result in visible downtime for users. Instead, goref supports working from a core file, but tools like gcore pause the process while they copy.

Instead livecore aims to generate subsecond pauses while the scanning phase before the pause and ELF core writing phase after the pause can take significantly longer.

Requirements

• Linux x86-64 (aarch64 patches welcome)
• Go 1.27

Usage

livecore [flags] <pid> <output.core>

Flags

• -passes N: Maximum pre-copy passes (default: 2)
• -dirty-thresh PCT: Stop when dirty < threshold (default: 5%)
• -concurrency N: Concurrent read workers (default: runtime.GOMAXPROCS)
• -verbose: Show progress and statistics

Installation

go install github.com/bradfitz/livecore@main

Building from Source

git clone https://github.com/bradfitz/livecore.git
cd livecore
go build -o livecore .

Apologies

This was my first (and so far only) vibe coding project, to see what all the rage was about. It was ... interesting.

So be very suspicious of this tool.

The core dump it generates is incomplete and testing so far has only involved goref consuming it.