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I want my spring batch job to run every 3 hours

I used expression * * */3 * * ? this starts the job at the hour that is divisible by 3 e.g. say the server was started at 2 PM the job starts executing only at 3 PM - so far so good but the job keeps starting every second! Is it because I used * in the 1st position?

I tried 0 0 */3 * * ? but it is erroring out. What is the best way to achieve this?

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2 Answers 2

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49

The format is

second, minute, hour, day, month, weekday

so the correct cron expression should be

0 0 */3 * * *

If that doesn't work, what's the exact error message you are getting?

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  • 21
    what is the difference between 0/3 and */3?
    – Ammad
    Feb 24, 2016 at 21:12
  • 2
    what is the difference 0/3 and */3?
    – shareef
    Jun 30, 2017 at 20:39
  • 2
    * means every possible value in the field. ? means you don't care about the value. It's used when you have two fields that may contradict each other.
    – Oleksandr Loushkin
    Oct 24, 2018 at 20:59
  • So I think */3 is every 3 hrs since the server started and 0/3 is every 3 hours where the hour is divisible by 3; so 3am, 6am, 9am, 12am, 3pm, 6pm, 9pm, 12pm. If anyone can confirm that would be great.
    – andrewps
    Apr 10, 2021 at 0:50
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    Ok I just ran a job with: 0 0 0/6 * * * to try for every 6 hours and it did work, it seemed to run every 6th whole hour after the server was started. I bounced it at 5:50pm and the job ran at 11pm, 5am, 11am. I would take a guess that */6 would run at exactly every 6 hours after the server was started in this case, 11:50pm, 5:50am and so on. So they both work but 0/6 is the 6th whole hour and */6 is exactly every 6 hours.
    – andrewps
    Apr 10, 2021 at 22:04
19

The right syntax to make the script to run every 3 hours is as below.

0 0 0/3 * * ?
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  • 14
    Spring cron jobs require 6 digits instead of 5
    – Anto
    Nov 25, 2015 at 10:05

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