Error 502 (GitLab is not responding) on Discussions of Merge Request

Summary

Error 502 (GitLab is not responding) on Discussions(56 comments) of Merge Request

Steps to reproduce

there are 56 comments on my merge request's diff, So I think if too many comments on one merge request, it will happens

What is the current bug behavior?

I can't see the comments

What is the expected correct behavior?

see 56 comments

Relevant logs and/or screenshots

微信截图_20190420195030

微信截图_20190420194935

Output of checks

(If you are reporting a bug on GitLab.com, write: This bug happens on GitLab.com)

Results of GitLab environment info

V11.4.3