In WT-7534, we investigated why FTDC stalls when a checkpoint occurs. Since checkpointing and retrieving statistics require a lock on the tables they work on, they cannot happen at the same time. The lock required by a checkpoint is WT_WITH_TABLE_READ_LOCK and the locks required by the statistics processing are WT_WITH_SCHEMA_LOCK and WT_WITH_TABLE_WRITE_LOCK in __wt_curstat_table_init.

Reproducing the issue:

The issue can be reproduced through the many-coll-test. It is possible to add a sleep inside WT_WITH_TABLE_READ_LOCK when the checkpoint requires it to emphasize the stalls. See this comment:

https://jira.mongodb.org/browse/WT-7534?focusedCommentId=3967202&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-3967202

Scope of the ticket:

• Find a solution to avoid those stalls coming from:
  • __wt_schema_open_indices
    • Suggestion: Before calling __wt_schema_open_indices, can we know if there are any indices ? Can we give the caller the possibility to skip those indices ?
  • And __wt_schema_get_table

Definition of done:

Agree on the best solution for the issue and create a new ticket to implement the solution.