Race condition running craft project-config/sync

[jwilm]

Description

As part of our production infra, we run a couple instances of CraftCMS to ensure availability. Our original deployment process had each instance running craft project-config/sync at startup. We changed that after finding this caused a race where duplicate sections and entries were being generated in the database. The net effect was that content for such entries could not be modified.

Steps to reproduce

1. Add a section/entry to local dev environment
2. Run project-config/sync twice in parallel against a separate database

Given that it's a race condition, it may take a few attempts to reproduce.

Additional info

• Craft version: 3.1.14
• PHP version: 7.0.33
• Database driver & version: PostgreSQL 10.3
• Plugins & versions: n/a