Issue Summary

When updating an attachment on a page with many incoming links, the request can be very slow or even timeout. This is due to attachment reconciliation which occurs in the background to ensure attachment consistency.

This is reproducible on Data Center: yes

Steps to Reproduce

1. Create a page and copy the link to the page (called main page)
2. Create 1500+ pages all having a hyperlink to the main page
3. Add or update an attachment on the main page

Expected Results

Reconciliation should only reconcile content that references the attachment, and the request should complete in a timely manner.

Actual Results

Reconciliation reconciles content that references the content an attachment is "attached to" causing unnecessary reconciliation - this causes the request to take longer than necessary.

In thread dumps you will find a majority of the request time in either:

• Pre 8.1 AttachmentRelatedContentReconciliationListener
• 8.1+ ReconcileReferringContentTask

Workaround

There are 3 known work-arounds:

• Minimise how many incoming links are coming into the page
• Optimise any Synchrony bottlenecks present in the system
• Disable collaborative editing