[DOCS-16365] [SERVER] Investigate changes in SERVER-80498: Improve thread safety of ReadConcernArgs modification Created: 04/Sep/23  Updated: 13/Nov/23  Resolved: 07/Nov/23

Status: Closed
Project: Documentation
Component/s: manual, Server
Affects Version/s: None
Fix Version/s: 7.2 Targeted, Server_Docs_20231113

Type: Task Priority: Minor - P4
Reporter: Backlog - Core Eng Program Management Team Assignee: Jeffrey Allen
Resolution: Works as Designed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Documented
documents SERVER-80498 Improve thread safety of ReadConcernA... Closed
Participants:
Days since reply: 13 weeks, 1 day ago

 Description   
Original Downstream Change Summary

$currentOp output for multi-document transactions used to display the actual readConcern being used. In some cases this could lead to intermittent instances of an operation displaying a different readConcern than the user-provided due to internal operations that temporarily changed it.

With the merged ticket, $currentOp will now display the user-provided readConcern without the possibility of intermittent changes.

Description of Linked Ticket

There is a harmless race between a thread performing an operation using DBDirectClient that temporarily resets the ReadConcernArgs (example) and the currentOps method reading the ReadConcernArgs of the target operation (code).

The main risk potential for this is an operation printing potentially wrong information for the read concern used. This would occur if the currentOp thread acquired a copy of the data while the temporary reset was happening.



 Comments   
Comment by Jeffrey Allen [ 07/Nov/23 ]

Thank you jordi.olivares-provencio@mongodb.com! Closing this ticket out as there's nothing for us to document here.

Comment by Jordi Olivares Provencio [ 07/Nov/23 ]

That is exactly the case here and you didn't miss anything!

Comment by Jeffrey Allen [ 06/Nov/23 ]

Hi jordi.olivares-provencio@mongodb.com! My interpretation of the docs changes summary for this ticket is that the readConcern returned by currentOp now matches the user-specified read concern, and no longer returns unexpected values. If that's the case, I'm not sure if there's anything for us to document here as this seems like a bug fix. If that all sounds correct, I'm inclined to close this ticket with no doc updates, given that the current description for the readConcern output does not mention the issue we fixed.

Let me know if I'm missing something!

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