Specific timezones cause high CPU load on UNIX systems using croner <= 7.x

[Earu]

Describe the bug When scheduling a function with croner on a specific timezone CPU load ramps up on UNIX systems (Linux/Macos), on Windows it functions normally.

To Reproduce

Cron("0 8 * * *", {
    timezone: "Europe/London",
}, async () => {
    console.log('test');
})

Expected behavior CPU Load shouldn't be that high considering the process only consists on one event waiting to be fired once everyday at 8:00.

[Hexagon]

Oh! Which timezone, if it's needed for debugging?

[Earu]

I have the same job scheduled for all these timezones:

Europe/Andorra Asia/Dubai Asia/Kabul America/Puerto_Rico America/Puerto_Rico Europe/Tirane Asia/Yerevan Africa/Lagos Antarctica/Casey America/Argentina/Buenos_Aires Pacific/Pago_Pago Europe/Vienna Antarctica/Macquarie America/Puerto_Rico Europe/Helsinki Asia/Baku Europe/Belgrade America/Barbados Asia/Dhaka Europe/Brussels Africa/Abidjan Europe/Sofia Asia/Qatar Africa/Maputo Africa/Lagos America/Puerto_Rico Atlantic/Bermuda Asia/Kuching America/La_Paz America/Puerto_Rico America/Araguaina America/Toronto Asia/Thimphu Africa/Maputo Europe/Minsk America/Belize America/Cambridge_Bay Asia/Yangon Africa/Lagos Africa/Lagos Africa/Lagos Europe/Zurich Africa/Abidjan Pacific/Rarotonga America/Punta_Arenas Africa/Lagos Asia/Shanghai America/Bogota America/Costa_Rica America/Havana Atlantic/Cape_Verde America/Puerto_Rico Asia/Bangkok Asia/Famagusta Europe/Prague Europe/Berlin Africa/Nairobi Europe/Berlin America/Puerto_Rico America/Santo_Domingo Africa/Algiers America/Guayaquil Europe/Tallinn Africa/Cairo Africa/El_Aaiun Africa/Nairobi Africa/Ceuta Africa/Nairobi Europe/Helsinki Pacific/Fiji Atlantic/Stanley Pacific/Guadalcanal Atlantic/Faroe Europe/Paris Africa/Lagos Europe/London America/Puerto_Rico Asia/Tbilisi America/Cayenne Europe/London Africa/Abidjan Europe/Gibraltar America/Danmarkshavn Africa/Abidjan Africa/Abidjan America/Puerto_Rico Africa/Lagos Europe/Athens Atlantic/South_Georgia America/Guatemala Pacific/Guam Africa/Bissau America/Guyana Asia/Hong_Kong America/Tegucigalpa Europe/Belgrade America/Port-au-Prince Europe/Budapest Asia/Jakarta Europe/Dublin Asia/Jerusalem Europe/London Asia/Kolkata Indian/Chagos Asia/Baghdad Asia/Tehran Africa/Abidjan Europe/Rome Europe/London America/Jamaica Asia/Amman Asia/Tokyo Africa/Nairobi Asia/Bishkek Asia/Bangkok Pacific/Kanton Africa/Nairobi America/Puerto_Rico Asia/Pyongyang Asia/Seoul Asia/Riyadh America/Panama Asia/Almaty Asia/Bangkok Asia/Beirut America/Puerto_Rico Europe/Zurich Asia/Colombo Africa/Monrovia Africa/Johannesburg Europe/Vilnius Europe/Brussels Europe/Riga Africa/Tripoli Africa/Casablanca Europe/Paris Europe/Chisinau Europe/Belgrade America/Puerto_Rico Africa/Nairobi Pacific/Kwajalein Europe/Belgrade Africa/Abidjan Asia/Yangon Asia/Choibalsan Asia/Macau Pacific/Guam America/Martinique Africa/Abidjan America/Puerto_Rico Europe/Malta Indian/Mauritius Indian/Maldives Africa/Maputo America/Bahia_Banderas Asia/Kuching Africa/Maputo Africa/Windhoek Pacific/Noumea Africa/Lagos Pacific/Norfolk Africa/Lagos America/Managua Europe/Brussels Europe/Berlin Asia/Kathmandu Pacific/Nauru Pacific/Niue Pacific/Auckland Asia/Dubai America/Panama America/Lima Pacific/Gambier Pacific/Bougainville Asia/Manila Asia/Karachi Europe/Warsaw America/Miquelon Pacific/Pitcairn America/Puerto_Rico Asia/Gaza Atlantic/Azores Pacific/Palau America/Asuncion Asia/Qatar Asia/Dubai Europe/Bucharest Europe/Belgrade Asia/Anadyr Africa/Maputo Asia/Riyadh Pacific/Guadalcanal Asia/Dubai Africa/Khartoum Europe/Berlin Asia/Singapore Africa/Abidjan Europe/Belgrade Europe/Berlin Europe/Prague Africa/Abidjan Europe/Rome Africa/Abidjan Africa/Nairobi America/Paramaribo Africa/Juba Africa/Sao_Tome America/El_Salvador America/Puerto_Rico Asia/Damascus Africa/Johannesburg America/Grand_Turk Africa/Ndjamena Asia/Dubai Africa/Abidjan Asia/Bangkok Asia/Dushanbe Pacific/Fakaofo Asia/Dili Asia/Ashgabat Africa/Tunis Pacific/Tongatapu Europe/Istanbul America/Puerto_Rico Pacific/Tarawa Asia/Taipei Africa/Nairobi Europe/Kyiv Africa/Nairobi Pacific/Pago_Pago America/Adak America/Montevideo Asia/Samarkand Europe/Rome America/Puerto_Rico America/Caracas America/Puerto_Rico America/Puerto_Rico Asia/Bangkok Pacific/Efate Pacific/Tarawa Pacific/Apia Asia/Riyadh Africa/Nairobi Africa/Johannesburg Africa/Maputo Africa/Maputo

[Hexagon]

Thanks, Will have a look asap

[Hexagon]

Looking into this. Parsing seem to be fine:

I'm also trying this code, with an additional log to ensure that there is no internal loop going bananas:

import { Cron } from "./src/croner.js";

console.log("Starting normal cron");
new Cron("* * * * * *", { maxRuns: 5}, async () => {
    console.log("Running normal cron")
});

setTimeout(() => {
    console.log("Starting timezoned cron");
    new Cron("* * * * * *", { maxRuns: 5, timezone: "Asia/Calcutta"}, async () => {
        console.log("Running timezoned cron")
    });        
}, 6000);

And the results seem fine, without any surge in CPU usage:

Using your cron pattern 0 8 * * * i get this output:

Which essentially means that croner is chunking up the waiting in 30 second pieces. Internally there is a setTimeout started which is waiting at most 30 seconds then re-checking how much time is left. Shouln't normally cause high cpu.

@Earu Which environment are you using (runtime and version, croner version, linux distro)?

[Earu]

I tested this both on a production linux server running Ubuntu 22.04.3 LTS and a intel macbook running Ventura 13.4.1.

Croner is ^7.0.5 and node is v21.4.0

I could observe the same behavior in both cases, all the logic of my script is done in callbacks there is nothing running aside from these callbacks.

A few suggestions to keep testing:

• Try scheduling multiple jobs on the same timezones
• Try scheduling like 10-20 jobs at once

[Hexagon]

Thanks, i'll have a look using a similar setup 👍

[Hexagon]

Currently using Debian 12, Node 21.4.0, Croner ^7.0.5, and running 2000 instances on an old laptop. Running this gives me a total system CPU usage of about 3-5% (which is unchanged from prior to starting the process).

hexagon@hexabox:~/git/test> uname -a
Linux hexabox 6.1.0-13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.55-1 (2023-09-29) x86_64 GNU/Linux
hexagon@hexabox:~/git/test> cat /etc/debian_version
12.2
hexagon@hexabox:~/git/test> node --version
v21.4.0
hexagon@hexabox:~/git/test> cat package.json | grep croner
    "croner": "^7.0.5"
hexagon@hexabox:~/git/test> cat test.js
import { Cron } from "croner";

for(let i = 0; i < 2000; i++) {
    Cron("0 8 * * *", {
        timezone: "Europe/London",
    }, async () => {
        console.log('test');
    });

However! With this next test, I do actually see a surge in CPU usage:

import { Cron } from "croner";

let uniqueTimeZones = [
    "Europe/Andorra",
    "Asia/Dubai",
    "Asia/Kabul",
    "America/Puerto_Rico",
    "Europe/Tirane",
    "Asia/Yerevan",
    "Africa/Lagos",
    "Antarctica/Casey",
    "America/Argentina/Buenos_Aires",
    "Pacific/Pago_Pago",
    "Europe/Vienna",
    "Antarctica/Macquarie",
    "Europe/Helsinki",
    "Asia/Baku",
    "Europe/Belgrade",
    "America/Barbados",
    "Asia/Dhaka",
    "Europe/Brussels",
    "Africa/Abidjan",
    "Europe/Sofia",
    "Asia/Qatar",
    "Africa/Maputo",
    "Atlantic/Bermuda",
    "Asia/Kuching",
    "America/La_Paz",
    "America/Araguaina",
    "America/Toronto",
    "Asia/Thimphu",
    "Europe/Minsk",
    "America/Belize",
    "America/Cambridge_Bay",
    "Asia/Yangon",
    "Europe/Zurich",
    "Pacific/Rarotonga",
    "America/Punta_Arenas",
    "Asia/Shanghai",
    "America/Bogota",
    "America/Costa_Rica",
    "America/Havana",
    "Atlantic/Cape_Verde",
    "Asia/Bangkok",
    "Asia/Famagusta",
    "Europe/Prague",
    "Europe/Berlin",
    "Africa/Nairobi",
    "America/Santo_Domingo",
    "Africa/Algiers",
    "America/Guayaquil",
    "Europe/Tallinn",
    "Africa/Cairo",
    "Africa/El_Aaiun",
    "Africa/Ceuta",
    "Pacific/Fiji",
    "Atlantic/Stanley",
    "Pacific/Guadalcanal",
    "Atlantic/Faroe",
    "Europe/Paris",
    "Europe/London",
    "Asia/Tbilisi",
    "America/Cayenne",
    "Europe/Gibraltar",
    "America/Danmarkshavn",
    "Europe/Athens",
    "Atlantic/South_Georgia",
    "America/Guatemala",
    "Pacific/Guam",
    "Africa/Bissau",
    "America/Guyana",
    "Asia/Hong_Kong",
    "America/Tegucigalpa",
    "America/Port-au-Prince",
    "Europe/Budapest",
    "Asia/Jakarta",
    "Europe/Dublin",
    "Asia/Jerusalem",
    "Asia/Kolkata",
    "Indian/Chagos",
    "Asia/Baghdad",
    "Asia/Tehran",
    "Europe/Rome",
    "America/Jamaica",
    "Asia/Amman",
    "Asia/Tokyo",
    "Asia/Bishkek",
    "Pacific/Kanton",
    "Asia/Pyongyang",
    "Asia/Seoul",
    "Asia/Riyadh",
    "America/Panama",
    "Asia/Almaty",
    "Asia/Beirut",
    "Asia/Colombo",
    "Africa/Monrovia",
    "Africa/Johannesburg",
    "Europe/Vilnius",
    "Europe/Riga",
    "Africa/Tripoli",
    "Africa/Casablanca",
    "Europe/Chisinau",
    "Pacific/Kwajalein",
    "Asia/Choibalsan",
    "Asia/Macau",
    "America/Martinique",
    "Europe/Malta",
    "Indian/Mauritius",
    "Indian/Maldives",
    "America/Bahia_Banderas",
    "Africa/Windhoek",
    "Pacific/Noumea",
    "Pacific/Norfolk",
    "America/Managua",
    "Asia/Kathmandu",
    "Pacific/Nauru",
    "Pacific/Niue",
    "Pacific/Auckland",
    "America/Lima",
    "Pacific/Gambier",
    "Pacific/Bougainville",
    "Asia/Manila",
    "Asia/Karachi",
    "Europe/Warsaw",
    "America/Miquelon",
    "Pacific/Pitcairn",
    "Asia/Gaza",
    "Atlantic/Azores",
    "Pacific/Palau",
    "America/Asuncion",
    "Europe/Bucharest",
    "Asia/Anadyr",
    "Pacific/Guadalcanal",
    "Africa/Khartoum",
    "Asia/Singapore",
    "Europe/Prague",
    "America/Paramaribo",
    "Africa/Juba",
    "Africa/Sao_Tome",
    "America/El_Salvador",
    "Asia/Damascus",
    "America/Grand_Turk",
    "Africa/Ndjamena",
    "Asia/Dushanbe",
    "Pacific/Fakaofo",
    "Asia/Dili",
    "Asia/Ashgabat",
    "Africa/Tunis",
    "Pacific/Tongatapu",
    "Europe/Istanbul",
    "Pacific/Tarawa",
    "Asia/Taipei",
    "Europe/Kyiv",
    "America/Adak",
    "America/Montevideo",
    "Asia/Samarkand",
    "America/Caracas",
    "Pacific/Efate",
    "Pacific/Apia"
];

const cronPattern = "0 8 * * *";

const instancesPerTimeZone = 10;

console.info(`Registering ${instancesPerTimeZone} (instances) * ${uniqueTimeZones.length} (time zones) = ${instancesPerTimeZone*uniqueTimeZones.length} cron instances running pattern '${cronPattern}'`);

for(let tzIdx = 0; tzIdx < uniqueTimeZones.length; tzIdx++) {
    for(let inst = 0; inst < instancesPerTimeZone; inst++) {
        Cron(cronPattern, {
            timezone: uniqueTimeZones[tzIdx],
        }, async () => {
            console.log('Run');
        });
    }
}

@Earu, I've narrowed it down to "America/Puerto_Rico" as one of the time zones causing this issue. However, it seems to be resolved in 8.0.0. If you're using Node 18 or higher in all your environments, can you try upgrading to ^8.0.0 to see if that fixes the issue for you?

Even if it does, please leave this issue open. I'll need to address this in the 7.x channel for legacy solutions, and I'll also have to figure out a safeguard to prevent this from happening in the 8.x channel.

[Earu]

Yep that worked! Both on the production server and my macbook! Thanks for the quick replies and help!

[Hexagon]

Resolved in 8.0.0 and potentially hotfixed for 7.x in croner@7.0.6-dev.2 and channel croner@legacy-node-support.

[Hexagon]

Now resolved in the 7.x branch through 7.0.7