Uploaded image for project: 'Documentation'
  1. Documentation
  2. DOCS-12990

Investigate changes in SERVER-41947: Disallow using the "system.views" collection name as the source or target names in the rename command

      Description

      Downstream Change Summary

      renaming "system.views" or renaming any collection to "system.views" via command is not allowed.

      Description of Linked Ticket

      This is a bug fix for a build failure where the following scenario leads to a deadlock:

      T1: Rename command is renaming 'test.coll' to 'test.system.views', so it has the MODE_IX on 'test' and MODE_X on both 'coll' and 'system.views'. The next step is to check if 'coll' is a view by calling the ViewCatalog::lookup() and waiting to acquire the ViewCatalog mutex which is currently held by T2.

      T2: Running CountCmd on a collection that didn't exist, but in AutoGetCollection we check if it could be a view and call ViewCatalog::lookup(), here we see that the ViewCatalog is invalidated, so we call _reloadIfNeeded. Now _reloadIfNeeded() uses the DurableViewCatalog::iterate but that requires the MODE_IS lock on the 'test.system.views' collection which is currently held by T1.

      So we have a deadlock where:
      T1 has MODE_X on 'test.system.views' but is waiting for ViewCatalog mutex.
      T2 has ViewCatalog mutex during reload and needs MODE_IS on 'test.system.views'.

      Scope of changes

      Impact to Other Docs

      MVP (Work and Date)

      Resources (Scope or Design Docs, Invision, etc.)

            Assignee:
            Unassigned Unassigned
            Reporter:
            backlog-server-pm Backlog - Core Eng Program Management Team
            Votes:
            0 Vote for this issue
            Watchers:
            2 Start watching this issue

              Created:
              Updated:
              Resolved:
              4 years, 19 weeks, 4 days ago