pm0

A fast, lightweight, PM2-compatible process supervisor written in Go. Same workflow and commands as PM2 (start, status, logs, scale, reload, ecosystem), a fraction of the memory footprint, and native support for any runtime (Node.js, Bun, Deno, Python, Go, Rust, and shell scripts).

Documentation & Benchmarks: pm0.thakur.dev

$ pm0 start api.js -i max        # cluster mode, one port, N workers
$ pm0 status
name │ id │ mode    │ pid  │ uptime │ ↺ │ status │ cpu  │ mem
api  │ 0  │ cluster │ 7731 │ 12s    │ 0 │ online │ 0.0% │ 46.6mb
api  │ 1  │ cluster │ 7738 │ 12s    │ 0 │ online │ 0.0% │ 46.6mb
$ pm0 reload api                 # rolling zero-downtime reload

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Features

• Low Memory Footprint: ~16 MB idle daemon RSS (77% less than PM2).
• Fast CLI: Sub-40ms status table response at scale.
• Standalone Daemon: Single static Go binary; does not require Node.js for the supervisor daemon.
• Multi-Runtime Support: Native execution for Node, Bun, Deno, Python, and compiled binaries.
• Process Reliability: Built on Linux cgroup v2 kill paths to guarantee zero orphaned child processes.
• Zero-Downtime Cluster Mode (Node.js only): Kernel SO_REUSEPORT socket pooling for rolling updates without dropped connections (Node ≥ 23.2; other runtimes stay fork-mode).
• Built-in Log Rotation: Memory-bounded ring buffers with automatic size-based rotation.

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Installation

Automated Install via curl (Recommended)

Detects architecture (amd64, arm64, arm, 386) and installs the binary:

# User install (installs to ~/.local/bin)
curl -fsSL https://pm0.thakur.dev/install.sh | bash

# System-wide install (installs to /usr/local/bin)
curl -fsSL https://pm0.thakur.dev/install.sh | sudo bash

If installing without sudo, ensure ~/.local/bin is in your $PATH (e.g., export PATH="$HOME/.local/bin:$PATH" in ~/.bashrc).

Direct Binary Download

Download the pre-compiled static binary directly:

# Linux amd64 (x86_64)
sudo curl -fsSL https://github.com/thakurdotdev/pm0/releases/latest/download/pm0-linux-amd64 -o /usr/local/bin/pm0 && sudo chmod +x /usr/local/bin/pm0

# Linux arm64 (aarch64)
sudo curl -fsSL https://github.com/thakurdotdev/pm0/releases/latest/download/pm0-linux-arm64 -o /usr/local/bin/pm0 && sudo chmod +x /usr/local/bin/pm0

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Quick Start

Starting Applications

# Node.js
pm0 start server.js --name web               # Single instance (fork mode)
pm0 start server.js -i max                   # Cluster mode (1 worker per CPU, shared port)

# Bun
pm0 start server.ts --interpreter bun --name bun-api

# Deno
pm0 start server.ts --interpreter deno --name deno-api

# Python
pm0 start app.py --name python-app           # Auto-detects python3

# Compiled Binaries (Go, Rust, C++)
pm0 start ./my-binary --interpreter none --name go-service

# Shell Scripts
pm0 start deploy.sh --name worker            # Auto-detects sh/bash

Process Management

pm0 status                           # View process status table
pm0 logs web --lines 100             # Stream logs with backlog
pm0 describe web                     # Detailed app metadata, uptime, and memory
pm0 scale web +2                     # Scale cluster workers up (+2) or down (-1)
pm0 reload web                       # Rolling zero-downtime reload
pm0 restart web                      # Hard restart
pm0 stop web                         # Stop process
pm0 delete web                       # Remove process from supervision

Persistence and Systemd

pm0 save                             # Save running process snapshot
pm0 resurrect                        # Restore saved processes
pm0 startup                          # Install systemd service for auto-boot

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HTTP API (opt-in)

pm0 can expose a local JSON/REST control plane for dashboards and co-located backend services — list processes with full PM2-compatible data, and act on them (start, stop, restart, reload, delete, scale, stream logs over SSE).

Off by default. Enable it with PM0_HTTP_ADDR (host:port or unix:/path), with pm0 daemon --http-addr, or by answering "yes" to the installer prompt (which writes $PM0_HOME/config):

PM0_HTTP_ADDR=127.0.0.1:9615 pm0 daemon

curl -s http://127.0.0.1:9615/api/v1/processes
curl -s -X POST http://127.0.0.1:9615/api/v1/processes/web/restart

It has no authentication of its own and is meant to be bound to loopback (or a Unix socket) only — your own backend terminates auth and re-exposes it. Full contract: docs/http-api.md.

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Common Flags

Flag	Shorthand	Description	Example
--name	-n	Assign an application name	--name api
--interpreter		Specify runtime binary (bun, deno, none)	--interpreter bun
--instances	-i	Number of instances (N or max; Node.js apps share one port via cluster mode, other runtimes run as fork families with no shared port)	-i max
--watch		Auto-restart on file changes in current directory	--watch
--max-memory-restart		Auto-restart if memory exceeds limit	--max-memory-restart 500M
--env		Inject environment variable	--env PORT=3000
--parallel	-p	stop/restart/delete: concurrent per-app RPCs. Default 1 = sequential (staggered downtime, ordered ids). reload stays sequential by design (zero-downtime + rollback).	pm0 restart all --parallel 4
--		Pass arguments directly to your script	-- --port 8080

Parallel restarts trade staggered downtime for speed: pm0 restart all restarts one app at a time (each port is empty for ~100ms in turn), while pm0 restart all --parallel 4 restarts up to 4 at once (faster wall-clock, but all selected ports go down together and N runtimes booting at once spikes CPU/RSS on small boxes). Per-app semantics are unchanged either way (SIGINT -> kill_timeout -> SIGKILL through the actor mailbox).

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Ecosystem File

pm0 supports PM2-compatible ecosystem.config.js configurations:

module.exports = {
  apps: [
    {
      name: "api",
      script: "./server.ts",
      interpreter: "bun",
      instances: 2,
      env: {
        PORT: 3000
      }
    }
  ]
};

Start the ecosystem config:

pm0 start ecosystem.config.js

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Benchmarks: pm0 vs PM2

Tested under identical workloads (2 vCPU / 3.9 GB Linux environment):

Metric	PM2 7.0.4	pm0 1.0.1	Difference
list @ 500 apps	245 ms	38.5 ms	6.4x faster
Ecosystem start @ 500 apps	1.97 s / 139 MB	0.31 s / 78 MB	6.3x faster, -44% RSS
Daemon RSS (idle)	69 MB	16 MB	-77% memory
Idle CPU @ 0 apps	0.033%	0.033%	Parity
Cluster -i 2 throughput	25.8k req/s	27.3k req/s	Higher throughput
1,200 restart ops	238 ms / 290 s	6.5 ms / 9.3 s	37x faster
Sustained 100 MB/s log flood	20.2% CPU	5.7% CPU	3.6x less CPU
Log rotation	Module required	Built-in	Size-based copytruncate

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Requirements

• Operating System: Linux (uses cgroup v2 or pgid process tracking)
• Cluster Mode: Node ≥ 23.2 (kernel ≥ 3.9 SO_REUSEPORT)
• Fork Mode: Supports any runtime or executable (Bun, Node, Python, Go, Rust, shell)

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Building from Source

Requires Go ≥ 1.26:

git clone https://github.com/thakurdotdev/pm0.git
cd pm0
make build
sudo make install    # Installs to /usr/local/bin (PREFIX overridable)

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License

MIT