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Catch port conflicts and runaway processes

See when two programs listen on the same port, a local server stops answering, or a process takes more memory or CPU than it should. Everything is read on this Mac, and nothing is sent anywhere.

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What CoIsland watches in Local dev

Each monitor kind brings its own query and its own card in the island.

How to catch port conflicts on your Mac

An SSH tunnel left open on 127.0.0.1:8080 shadows the dev server you just started on *:8080, and localhost:8080 shows the wrong app. A Port conflicts monitor reads this Mac’s listening ports every minute and alerts when two programs share one.

-- name: Port conflicts
-- kind: localdev.conflicts
-- connector: local
-- every: 1m

port:any

port:any watches every port. port:3000, port:3000,5432 or port:3000-3999 narrow it. Connect Local dev covers all four kinds and their filters. Docker watches the containers on the same Mac, and all connectors share one page.

Connect it in three steps

  1. Add a Local dev connector. It asks only for a name, and one covers the whole Mac.

  2. Pick a monitor kind and what it watches, like port:3000-3999, program:node or memory:4GB.

  3. Port conflicts and Heavy processes also come as recommended monitors, added in one click. Each checks every minute unless you change it.

Built for Local dev

  • Read only. It never stops or signals a process.
  • No token and nothing to install. It reads this Mac's port table and process list, and sends nothing anywhere.
  • A limit alerts once when it's crossed, and again only after it came back under.
  • Memory is counted as Activity Monitor counts it, so the numbers match.

Then hand it to an agent

A click on the alert opens the agent in a terminal under it, with the whole alert as its first message.

Local dev questions

What counts as a port conflict?

Two different programs listening on the same TCP port, such as a Docker container and a local Postgres both on 5432. One program on both IPv4 and IPv6 is not a conflict, and neither are a server's own workers.

Why does a system process show no memory or CPU?

Only your own processes are readable. Heavy processes watches the ones that run as you and leaves system daemons out.

Can it free a port or stop a process?

No. It only reads, and never stops or signals a process. The alert says which program holds the port, and what to stop is up to you.

Does it watch UDP ports or other machines?

No. It reads TCP ports and processes on this Mac only.

Other connectors

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