Sync between GitLab.com & JIRA Data Center Edition via DVCS is delayed

Summary

A customer is experiencing delays in the sync between their GitLab.com projects and their JIRA Data Center instance and sees a number of 500 and 404 errors in logs on the JIRA side. The instance holds the following number of objects:

Archived Issues (Total) 1008
Archived Projects 28
Attachments 307623
Comments 1170060
Components 3733
Custom Fields 379
Groups 53
Individually Archived Issues 587
Issue Security Levels 1
Issue Types 77
Issues 921051
Issues In Archived Projects 421
Priorities 7
Projects 824
Resolutions 13
Screen Schemes 97
Screens 135
Statuses 90
Users 29433
Versions 254107
Workflows 21

It's speculated that the JIRA integration may not be able to facilitate a non-delayed sync between these two systems when this much data is involved, but GitLab Support is unclear on that so far. An investigation for this customer into whether or not a delay should be expected with this amount of data is required.

Steps to reproduce

Support has yet to be able to reproduce this issue as we do not have the means to simulate the integration between JIRA and GitLab.com with a JIRA instance of this scale.

Example Project

An example project is referenced in the Zendesk ticket below.

What is the current bug behavior?

Issues and merge requests currently experience a delay in syncing their statuses between JIRA and GitLab.com.

What is the expected correct behavior?

We expect that there will not be much of a delay in the sync of merge requests and issues between JIRA and GitLab.com.

Relevant logs and/or screenshots

Logs from the Atlassian side (displaying 500 and 404 errors) can be found in the Zendesk ticket below. Access to it (GitLab Internal only) can be requested via this process.

Output of checks

This bug happens on GitLab.com: 13.5.0-pre cb2cf8fd2c8

Zendesk Reports (GitLab Internal)