Issue Summary

A number of email notifications are showing a message "Error rendering diff:". This issue happens when we edit a page and save it. sometimes, we receive the page edit email notification with diff timeout message. Please see the attachment.

This issue is difficult to reproduce though, but we can see the diff timeout error in splunk logs for hello and prod. Here is the dashboard : https://splunk.paas-inf.net/en-US/app/search/hot89196_clone.

The root cause of this error is calculateDiff() function. The exception is thrown from here:  https://stash.atlassian.com/projects/CONFCLOUD/repos/confluence/browse/confluence-core/confluence/src/java/com/atlassian/confluence/diff/DaisyHtmlDiffer.java#142

confluence-notifications plugin calls this calculateDiff() function internally. This function is also called when we go to page history and compare two versions.

Steps to Reproduce

1. Edit a page and save it.
2. We should receive, page edit notification
3. Page edit email notification doesn't contain the diff, but a message "Error rendering diff during daisydiff. with timeout 40000"
4. However, the easier way to figure out this issue would be by stack trace in dashboard above. 

Expected Results

Page edit email should contain diff of the change in the content.

Actual Results

Page edit email notification doesn't contain the diff, but a message "Error rendering diff during daisydiff. with timeout 40000"

Workaround

The diff is currently excluded from the page edited notification email if diff generation times out.