Pm2: Error [ERR_IPC_CHANNEL_CLOSED]: channel closed

[marcosc90]

What's going wrong?

When shutting down my server which has a graceful shutdown using PM2 I get the following error:

Error [ERR_IPC_CHANNEL_CLOSED]: channel closed
    at process.target.send (internal/child_process.js:557:16)
    at ipcSend (/usr/lib/node_modules/pm2/node_modules/pmx/lib/utils/transport.js:22:13)
    at Object.Transport.send (/usr/lib/node_modules/pm2/node_modules/pmx/lib/utils/transport.js:34:3)
    at Timeout._onTimeout (/usr/lib/node_modules/pm2/node_modules/pmx/lib/Probe.js:120:17)
    at ontimeout (timers.js:488:11)
    at Timer.unrefdHandle (timers.js:599:5)

This does not happen when I run the server without PM2. The server shuts down perfectly, allowing ongoing connections to finish.

How could we reproduce this issue?

const cluster = require("cluster");

if (cluster.isMaster) {

    // Fork workers.
    for (let i = 0; i < 2; i++)
        cluster.fork();

    process.on('SIGINT', function() {
        console.log("SIGINT signal received: Master");
        for (let id in cluster.workers) {
            let worker = cluster.workers[id];

            worker.send({
                cmd: 'disconnect'
            });

            worker.disconnect();
        }

    });

} else {

    process.on('SIGINT', function() {});

    process.on("message", (msg) => {

        if (msg.cmd === 'disconnect') {
            console.log("disconnecting server " + process.pid);

            setTimeout(() => {
                console.log("Gracefully closed!");
            }, 10000);
        }

    });

}

Running the snippet with node, the process gracefully shuts down.

node test.js

Send SIGINT signal to process.

^CSIGINT signal received MASTER
disconnecting server 22596
disconnecting server 22601
Gracefully closed!
Gracefully closed!

But when using:

pm2 start test.js
pm2 stop test

I get:

1|test     | SIGINT signal received MASTER
1|test     | disconnecting server 22231
1|test     | disconnecting server 22232
1|test     | Process disconnected from parent !
1|test     | Error [ERR_IPC_CHANNEL_CLOSED]: channel closed
1|test     |     at process.target.send (internal/child_process.js:551:16)
1|test     |     at ipcSend (/usr/local/lib/node_modules/pm2/node_modules/pmx/lib/utils/transport.js:22:13)
1|test     |     at Object.Transport.send (/usr/local/lib/node_modules/pm2/node_modules/pmx/lib/utils/transport.js:33:3)
1|test     |     at Timeout._onTimeout (/usr/local/lib/node_modules/pm2/node_modules/pmx/lib/Probe.js:120:17)
1|test     |     at ontimeout (timers.js:488:11)
1|test     |     at Timer.unrefdHandle (timers.js:599:5)
1|test     | Process disconnected from parent !
1|test     | Error [ERR_IPC_CHANNEL_CLOSED]: channel closed
1|test     |     at process.target.send (internal/child_process.js:551:16)
1|test     |     at ipcSend (/usr/local/lib/node_modules/pm2/node_modules/pmx/lib/utils/transport.js:22:13)
1|test     |     at Object.Transport.send (/usr/local/lib/node_modules/pm2/node_modules/pmx/lib/utils/transport.js:33:3)
1|test     |     at Timeout._onTimeout (/usr/local/lib/node_modules/pm2/node_modules/pmx/lib/Probe.js:120:17)
1|test     |     at ontimeout (timers.js:488:11)
1|test     |     at Timer.unrefdHandle (timers.js:599:5)

Adding this line:

 if(e.code != "ERR_IPC_CHANNEL_CLOSED")
            process.exit(1);

in /usr/lib/node_modules/pm2/node_modules/pmx/lib/utils/transport.js fixes the problem but I'm not certain of the repercussions.

try {
    process.send(JSON.parse(stringify(args)));
  } catch(e) {
    console.error('Process disconnected from parent !');
    console.error(e.stack || e);
    if(e.code != "ERR_IPC_CHANNEL_CLOSED")
            process.exit(1);
  }

PM2 version: 2.4.6
Node version: 8.0.0 & 8.1.4
Ubuntu 16.04

[Unitech]

Are you starting this code in fork mode or cluster mode?

Btw pm2 cluster mode automatically handle the cluster module for you so you don't have to write this logic

[marcosc90]

Fork mode using:
pm2 start test.js

Yes I know it can handle the cluster module, but I need the code to be able to use cluster mode without depending on PM2.

[vmarchaud]

@marcosc90 Just use the --no-pmx flag when using the CLI and pmx: false when using a ecosystem file, it should not load this portion of code.

[marcosc90]

@vmarchaud Thanks It's working perfectly without pmx!

[juncode]

@marcosc90 Just use the --no-pmx flag when using the CLI and pmx: false when using a ecosystem file, it should not load this portion of code.

Thanks It's a good way