Skip Redundant Persistent Ref existence check

Merged Shinya Maeda requested to merge remove-redundant-persistent-ref-check into master

What does this MR do?

This MR is to skip the redundant persistent ref existence check. This pressurizes Gitaly nodes and if timeout happens, it could end up fetching all refspecs in runner. The assumption was described by @stanhu at gitlab-com/gl-infra/production#2143 (comment 343690877)

Ok, maybe this is what happened based on https://log.gprd.gitlab.net/goto/15e8e5a9084502a3b17113fa0e0c1e60:

  1. The ref did, in fact, exist. It seems like there are many chances to create the ref since every build attempts to do so.
  2. However, the RefExists call timed out.
  3. As a result, https://gitlab.com/gitlab-org/gitlab/blob/2bfe8f06724470576e408f3cc282a30f0c271880/app/models/ci/persistent_ref.rb#L18-19 returned false, and the CI pipeline got an empty refspec.

I still wonder why so many RPCs were stalling out, but perhaps we should cache the existence of this ref?

Screenshots

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

  • Label as security and @ mention @gitlab-com/gl-security/appsec
  • The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • Security reports checked/validated by a reviewer from the AppSec team
Edited by Shinya Maeda