Node.js tcp socket shut off trigger

Question

I use node.js with the NET class to connect multiple Rasperry Pi's.

//Server
const net = require('node:net');
const server = net.createServer();

//Client
const tcpConnect = net.createConnection(SERVERINFO);

Thereby I can easily register multiple clients, open/close streams. Everything works without any problems.

But now I noticed that the callbacks.

tcpConnect.on('end', () => { console.log('end triggered') });
tcpConnect.on('close', () => { console.log('close triggered') });
tcpConnect.on('error', () => { console.log('error triggered') });

do not work if the server suddenly has a power failure (e.g. power supply is pulled). The clients don't trigger an error/end or close, so I can't close the connection properly. As a result, an error is not triggered until the next attempt to write something to an existing stream. But this is not an option for me, especially for "online monitoring".

Does anyone know a way to identify the shut off of the server immediately?

lossleader · Accepted Answer · 2022-05-17 10:58:52Z

2

+50

You need to enable TCP keep-alives in order for the client to detect that the server is no longer responding and you can tune how often it checks on an idle connection. (I've written a language generic description at the beginning of this answer.)

In node it appears you can do this: socket.setKeepAlive(true), i.e. for this client to detect the server is gone when the socket is idle:

//Client
const tcpConnect = net.createConnection(SERVERINFO);
tcpConnect.setKeepAlive(true);

edited May 17, 2022 at 10:58

answered May 14, 2022 at 10:49

lossleader

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1 Comment

Interface Over a year ago

Unfortunately, this is not immediate. However, I have not found a better approach even after extensive research. Many thanks for the support

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