8.5 Backport: "Next Execution" in Scheduled Jobs panel displays timestamps in the past

Backport justification - This issue has a very high impact to the PS customers, , since the fix release is a non LTS version and will take time/efforts/tests for the customer to wait for an LTS and upgrade, we’re asking this to be backported to a current latest LTS version 7.19.x.

Value in backporting - Customers will continue on an LTS version and will be able to proceed with their operations.

Effort to backport -

Risk in backporting - 

Version(s) to target - 8.5

Quality Plan -

Original Ticket Description:{}

Issue Summary

In Confluence Admin > Scheduled Jobs, the "Next Execution" timestamp can show timestamps in the past under certain conditions.

It seems that "Next Execution" is calculated when Confluence is started up, OR if the cron expression for the scheduled job is modified, and stores somewhere (likely in-memory). Subsequently, if that job is ran manually, then the "Next Execution" reverts incorrectly to the stored value instead of displaying the next run time. In other words, It appears to be loading a cached value that is no longer valid.

This appears to be a display problem only, as the job continues to run on schedule despite the backdated "Next Execution" value shown.

Steps to Reproduce

1. Start Confluence
2. Navigate to Confluence Admin > Scheduled Jobs
3. Wait for a few minutes for some scheduled jobs to run. "Flush Task Queue" is a good one to test wiith since it runs every minute.
4. Click "Run" on the scheduled job to manually run it
5. After the job runs, click Refresh in web browser

Expected Results

After the scheduled job runs, "Next Execution" is updated to show the next scheduled time to run in the future

Actual Results

"Next execution" reverts back to the original timestamp calculated during startup, which is now outdated. Hence, status is not shown correctly and history not updated.

Workaround

none

Other notes

• In local testing, if the scheduled job is allowed to run on its own (i.e. not manually triggered) then the "Next Execution" time will be displayed correctly afterwards. However, running the job manually then refreshing the browser afterwards again will re-trigger the bug
• This is not a problem with local browser cache and can be reproduced even when browser cache is cleared
• The cached value is also not flushable via the UI at Confluence Admin > Cache Management. However, a restart will clear this