To explain my situation. I have a pm2 cron script that I run using:

pm2 start clear-redis-state-cron.js -n clearState --cron '0 0/1 * 1/1 * *'

This runs the js script called clear-redis-state-cron.js just fine.

The role of this script is to stop process p1 and process p2. It then runs a lua redis script that clears some keys from the database. This all works fine but I've put it here for brevity.

var crs = require('./clear-redis-state'),
    pm2 = require('pm2');

pm2.connect(function(err) {
    pm2.stop('ponent1');
    pm2.stop('ponent2');

    crs.clear();

    pm2.restart(__dirname + '/../../node_modules/ponent1/index.js', { name: 'c1' }, function (err, proc) {
        if (err) throw new Error('err');
    });

    pm2.restart(__dirname + '/../../node_modules/ponent2/index.js', { name: 'c2' }, function (err, proc) {
        if (err) throw new Error('err');
    });
});

It runs a clear() js function which is defined here:

var config = require('mon/lib/config'),
    log = require('mon/lib/logger'),
    redis = require('mon/lib/redis'),
    ScriptTo = require('redis-scripto');

exports.clear = function() {
    log.init();

    if (!config.isSet()) {
        // Use local config
        var configPath = require('path').join(__dirname, '../../app/config');
        config.load(configPath);
    }

    redis.init(config.get('redis'));

    var scriptManager = new ScriptTo(redis.getClient());
    scriptManager.loadFromDir(__dirname + '/scripts');

    scriptManager.run('clear-state', [], [], function(err, results) {
        logError(err);
        console.log('results:', results);
    });

    function logError(err) {
        if (err !== null) {
            console.log('Error loading lua script merge-keys: ', err);
        }
    };
}

I have no problems with that. However, it seems to crash on start. Let's say I already have pm2 running two processes ponent1 and ponent2 called p1 and p2 respectively. Why would I get the following error when starting the cron when I run it with --no-daemon?

... clear-redis-state-cron.js had too many unstable restarts (15). Stopped. "errored"

My hunch is that either the process is starting up shutting down incorrectly and is in the wrong state as a result so when it tries to close it it's already closed, but because pm2 assumes something went wrong the cron process is stopped.

Any ideas what I might be doing wrong?

Edit: I tried promisifying my shutdown pm2 logic like so:

pm2.connect(function(err) {

    Promise.resolve(ops.stop('ponent1'))
       .then(ops.stop('ponent2'))
       .then(ops.clear)
       .then(ops.restart(__dirname + '/../../node_modules/ponent1/index.js', { name: 'ponent1' }))
       .then(ops.restart(__dirname + '/../../node_modules/ponent2/index.js', { name: 'ponent2' }))
       .catch(logFailureToStop);
});

var logFailureToStop = function (err) {
    console.log('Failed to stop ', err);
};

With following result after stopping processes that are running:

$ pm2 list
┌───────────┬────┬──────┬───────┬─────────┬───────────┬────────┬─────────────┬──────────┐
│ App name  │ id │ mode │ PID   │ status  │ restarted │ uptime │      memory │ watching │
├───────────┼────┼──────┼───────┼─────────┼───────────┼────────┼─────────────┼──────────┤
│ ponent2│ 0  │ fork │ 0     │ stopped │        17 │ 0      │      0 B    │ disabled │
│ ponent1│ 1  │ fork │ 18769 │ online  │        31 │ 19s    │ 30.539 MB   │ disabled │

To explain my situation. I have a pm2 cron script that I run using:

pm2 start clear-redis-state-cron.js -n clearState --cron '0 0/1 * 1/1 * *'

This runs the js script called clear-redis-state-cron.js just fine.

The role of this script is to stop process p1 and process p2. It then runs a lua redis script that clears some keys from the database. This all works fine but I've put it here for brevity.

var crs = require('./clear-redis-state'),
    pm2 = require('pm2');

pm2.connect(function(err) {
    pm2.stop('ponent1');
    pm2.stop('ponent2');

    crs.clear();

    pm2.restart(__dirname + '/../../node_modules/ponent1/index.js', { name: 'c1' }, function (err, proc) {
        if (err) throw new Error('err');
    });

    pm2.restart(__dirname + '/../../node_modules/ponent2/index.js', { name: 'c2' }, function (err, proc) {
        if (err) throw new Error('err');
    });
});

It runs a clear() js function which is defined here:

var config = require('mon/lib/config'),
    log = require('mon/lib/logger'),
    redis = require('mon/lib/redis'),
    ScriptTo = require('redis-scripto');

exports.clear = function() {
    log.init();

    if (!config.isSet()) {
        // Use local config
        var configPath = require('path').join(__dirname, '../../app/config');
        config.load(configPath);
    }

    redis.init(config.get('redis'));

    var scriptManager = new ScriptTo(redis.getClient());
    scriptManager.loadFromDir(__dirname + '/scripts');

    scriptManager.run('clear-state', [], [], function(err, results) {
        logError(err);
        console.log('results:', results);
    });

    function logError(err) {
        if (err !== null) {
            console.log('Error loading lua script merge-keys: ', err);
        }
    };
}

I have no problems with that. However, it seems to crash on start. Let's say I already have pm2 running two processes ponent1 and ponent2 called p1 and p2 respectively. Why would I get the following error when starting the cron when I run it with --no-daemon?

... clear-redis-state-cron.js had too many unstable restarts (15). Stopped. "errored"

My hunch is that either the process is starting up shutting down incorrectly and is in the wrong state as a result so when it tries to close it it's already closed, but because pm2 assumes something went wrong the cron process is stopped.

Any ideas what I might be doing wrong?

Edit: I tried promisifying my shutdown pm2 logic like so:

pm2.connect(function(err) {

    Promise.resolve(ops.stop('ponent1'))
       .then(ops.stop('ponent2'))
       .then(ops.clear)
       .then(ops.restart(__dirname + '/../../node_modules/ponent1/index.js', { name: 'ponent1' }))
       .then(ops.restart(__dirname + '/../../node_modules/ponent2/index.js', { name: 'ponent2' }))
       .catch(logFailureToStop);
});

var logFailureToStop = function (err) {
    console.log('Failed to stop ', err);
};

With following result after stopping processes that are running:

$ pm2 list
┌───────────┬────┬──────┬───────┬─────────┬───────────┬────────┬─────────────┬──────────┐
│ App name  │ id │ mode │ PID   │ status  │ restarted │ uptime │      memory │ watching │
├───────────┼────┼──────┼───────┼─────────┼───────────┼────────┼─────────────┼──────────┤
│ ponent2│ 0  │ fork │ 0     │ stopped │        17 │ 0      │      0 B    │ disabled │
│ ponent1│ 1  │ fork │ 18769 │ online  │        31 │ 19s    │ 30.539 MB   │ disabled │

• javascript
• cron
• pm2

1 Answer 1

Managed to resolve this issue in the end.

The issue was caused because I had an on handler event listening into SIGTERM. Apparently these interfere with PM2 so you need to instead use the gracefulStop/gracefulRestart mands.

See: https://github./Unitech/PM2/issues/304