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"0 1 30 3 *" creates infinite loop #919

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AndreMaz opened this issue Nov 15, 2024 · 5 comments · Fixed by #938
Closed

"0 1 30 3 *" creates infinite loop #919

AndreMaz opened this issue Nov 15, 2024 · 5 comments · Fixed by #938
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released type:bug Bug reports and bug fixes

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@AndreMaz
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Description

The following snippet blocks the process

import { CronJob } from "cron";
const job2 = new CronJob(
  "0 1 30 3 *",
  function () {
    console.log("You will see this message every second");
  }, // onTick
  null, // onComplete
  false, // start
  "Europe/Lisbon" // timeZone
);

console.log(job2.nextDates(1));

Expression at crontab.guru
image

What causes the issue is the fact that in Portugal the daylight savings starts at Mar 30 so the 01:00 does not actually exist.

Expected Behavior

Next execution date to be returned or an error/ warning to be shown

Actual Behavior

The process hangs forever

Possible Fix

Steps to Reproduce

Context

Your Environment

  • cron version: 3.2.1
  • NodeJS version: v20.14.0
  • Operating System and version: Ubuntu LTS 24.04
@AndreMaz
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Attached the debugger and tried to see what's going on.

Turns out that it gets "stuck" in while(true) {} statement in getNextDateFrom() method
image

Added a console.log to see the dates that it was generating. Here's the list:

2025-03-30T00:00:00.000+00:00 86400000
2025-03-30T02:00:00.000+01:00 90000000
2025-03-30T03:00:00.000+01:00 93600000
2025-03-30T04:00:00.000+01:00 97200000
2025-03-30T05:00:00.000+01:00 100800000
2025-03-30T06:00:00.000+01:00 104400000
2025-03-30T07:00:00.000+01:00 108000000
2025-03-30T08:00:00.000+01:00 111600000
2025-03-30T09:00:00.000+01:00 115200000
2025-03-30T10:00:00.000+01:00 118800000
2025-03-30T11:00:00.000+01:00 122400000
2025-03-30T12:00:00.000+01:00 126000000
2025-03-30T13:00:00.000+01:00 129600000
2025-03-30T14:00:00.000+01:00 133200000
2025-03-30T15:00:00.000+01:00 136800000
2025-03-30T16:00:00.000+01:00 140400000
2025-03-30T17:00:00.000+01:00 144000000
2025-03-30T18:00:00.000+01:00 147600000
2025-03-30T19:00:00.000+01:00 151200000
2025-03-30T20:00:00.000+01:00 154800000
2025-03-30T21:00:00.000+01:00 158400000
2025-03-30T22:00:00.000+01:00 162000000
2025-03-30T23:00:00.000+01:00 165600000
2025-03-30T00:00:00.000+00:00 86400000 <----- WE'RE BACK TO SAME DATE
2025-03-30T02:00:00.000+01:00 90000000
2025-03-30T03:00:00.000+01:00 93600000
2025-03-30T04:00:00.000+01:00 97200000
2025-03-30T05:00:00.000+01:00 100800000
2025-03-30T06:00:00.000+01:00 104400000
2025-03-30T07:00:00.000+01:00 108000000
2025-03-30T08:00:00.000+01:00 111600000
2025-03-30T09:00:00.000+01:00 115200000
2025-03-30T10:00:00.000+01:00 118800000
2025-03-30T11:00:00.000+01:00 122400000
2025-03-30T12:00:00.000+01:00 126000000
2025-03-30T13:00:00.000+01:00 129600000
2025-03-30T14:00:00.000+01:00 133200000
2025-03-30T15:00:00.000+01:00 136800000
2025-03-30T16:00:00.000+01:00 140400000
2025-03-30T17:00:00.000+01:00 144000000
2025-03-30T18:00:00.000+01:00 147600000
2025-03-30T19:00:00.000+01:00 151200000
2025-03-30T20:00:00.000+01:00 154800000
2025-03-30T21:00:00.000+01:00 158400000
2025-03-30T22:00:00.000+01:00 162000000
2025-03-30T23:00:00.000+01:00 165600000

Unfortunately I don't have enough knowledge about lib internals to solve this issue.

@sheerlox can you take a look at this?

@AndreMaz AndreMaz changed the title "0 1 30 3 *" causes process to hang "0 1 30 3 *" creates infinite loop Nov 21, 2024
@intcreator
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we rely on Luxon for most of our international date/time support so it's possible this is due to Luxon not handling that time period correctly

@intcreator intcreator added the type:bug Bug reports and bug fixes label Dec 11, 2024
sheerlox added a commit to sheerlox/node-cron that referenced this issue Dec 29, 2024
@sheerlox
test: add test case for kelektiv#919
2b17fcc
@sheerlox
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sheerlox commented Dec 29, 2024 •
edited
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Found the bug, PR on the way. Sorry for the delay 😓

@sheerlox
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sheerlox commented Dec 29, 2024 •
edited
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I've been running more tests to confirm I found the issue, and this bug actually affects to all time zones.

@sheerlox sheerlox mentioned this issue Dec 29, 2024
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intcreator pushed a commit that referenced this issue Dec 30, 2024
@sheerlox
fix: fix infinite loop on expressions resolving only inside a DST for…
efb8df5 
…ward jump (#938)

## Description

Removes a superfluous `+ 1` modifying the behavior unexpectedly. Using
the debugger I've located the bug to this instruction, and it can easily
be confirmed that this `+ 1` is the issue, since `date.month` &
`this.month` are both indexed starting from `1` (and not `0`).

Not sure how long this bug has been around, but it was [already present
when we aligned with the UNIX
standard](https://github.com/kelektiv/node-cron/pull/667/files#diff-c14c2dca8456f15417b39cfbd9758009f8eb4f3a190a415768d6e4ae6ae9dceeL473-L477).

## Related Issue

Fixes #919.

## Motivation and Context

Fixes an infinite loop when a cron expression only resolves to inside a
DST jump. See #919 for more.

## How Has This Been Tested?

Added two new test cases, and [made sure they triggered the infinite
loop](https://github.com/kelektiv/node-cron/actions/runs/12539141178/attempts/1?pr=938)
before writing the fix.

## Screenshots (if appropriate):

## Types of changes

<!--- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->

- [X] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)

## Checklist:

- [X] My code follows the code style of this project.
- [ ] My change requires a change to the documentation.
- [ ] I have updated the documentation accordingly.
- [X] I have added tests to cover my changes.
- [X] All new and existing tests passed.
- [ ] If my change introduces a breaking change, I have added a `!`
after the type/scope in the title (see the Conventional Commits
standard).
@ncb000gt
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🎉 This issue has been resolved in version 3.3.2 🎉

The release is available on:

Your semantic-release bot 📦🚀

intcreator pushed a commit to sheerlox/node-cron that referenced this issue Dec 30, 2024
@semantic-release-bot
Release v3.3.2 [skip ci]
7ed34cb 
## [3.3.2](kelektiv/node-cron@v3.3.1...v3.3.2) (2024-12-30)

### 🐛 Bug Fixes

* fix infinite loop on expressions resolving only inside a DST forward jump ([kelektiv#938](kelektiv#938)) ([efb8df5](kelektiv@efb8df5)), closes [/github.com/kelektiv/pull/667/files#diff-c14c2dca8456f15417b39cfbd9758009f8eb4f3a190a415768d6e4ae6ae9dceeL473-L477](https://github.com/kelektiv//github.com/kelektiv/node-cron/pull/667/files/issues/diff-c14c2dca8456f15417b39cfbd9758009f8eb4f3a190a415768d6e4ae6ae9dceeL473-L477) [kelektiv#919](kelektiv#919) [kelektiv#919](kelektiv#919)

### ⚙️ Continuous Integrations

* **action:** update marocchino/sticky-pull-request-comment action to v2.9.0 ([kelektiv#930](kelektiv#930)) ([1e7bce9](kelektiv@1e7bce9))
* **renovate:** pin GitHub action digests to semver ([kelektiv#926](kelektiv#926)) ([6541167](kelektiv@6541167))

### ♻️ Chores

* **deps:** lock file maintenance ([70c3339](kelektiv@70c3339))
* **deps:** lock file maintenance ([afad454](kelektiv@afad454))
* **deps:** lock file maintenance ([b1dbf69](kelektiv@b1dbf69))
* **deps:** pin dependencies ([kelektiv#915](kelektiv#915)) ([dfcbd3c](kelektiv@dfcbd3c))
* **deps:** update dependency [@commitlint](https://github.com/commitlint)/cli to v19.6.1 ([7999427](kelektiv@7999427))
* **deps:** update dependency [@semantic-release](https://github.com/semantic-release)/release-notes-generator to v14.0.2 ([93c9373](kelektiv@93c9373))
* **deps:** update dependency [@types](https://github.com/types)/node to v20.17.10 ([9313ffd](kelektiv@9313ffd))
* **deps:** update dependency lint-staged to v15.2.11 ([100c9ff](kelektiv@100c9ff))
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fix: fix infinite loop on expressions resolving only inside a DST forward jump sheerlox/node-cron
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@ncb000gt @AndreMaz @sheerlox @intcreator