[COMPASS-6307] Investigate changes in SERVER-68803: Add whether SBE is in use to currentOp output Created: 15/Nov/22  Updated: 28/Nov/22  Resolved: 28/Nov/22

Status: Closed
Project: Compass
Component/s: None
Affects Version/s: None
Fix Version/s: No version

Type: Investigation Priority: Major - P3
Reporter: Backlog - Core Eng Program Management Team Assignee: Anna Henningsen
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
depends on SERVER-68803 Add whether SBE is in use to currentO... Closed
Documentation Changes: Not Needed

 Description   
Original Downstream Change Summary

Added a queryFramework field to the currentOp output for query and getMore commands.

Description of Linked Ticket

It would be helpful to distinguish whether active queries are using the SBE or classic engines, in case there's ever a problem where SBE specifically is misbehaving, versus the classic engine, when both are running on a mongod depending on the query. 

I did some investigation into adding flags to currentOp output, so I've added some notes below in case it is helpful.

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The info should be carried across to getMore cmds, so it looks like the info will need to hook into/through the ClientCursor (perhaps a flag on the PlanExecutor the ClientCursor holds). The decision whether to use SBE appears to take place in getExecutor. So perhaps inside the getSlotBasedExecutor where OpDebug info is set (this will ultimately go into <db>.system.profile after the operation is done), we can add setting a flag on CurOp.

I'm unfamiliar with if there are any nesting problems to worry about, e.g. the DBDirectClient and leaving CurOp flags set when no longer running a query, or perhaps even subsequently running a query that uses the classic engine. Granted, that sounds like a problem for internal server operations, rather than user initiated operations. I'm not sure what the status quo is for this type of thing.



 Comments   
Comment by Anna Henningsen [ 28/Nov/22 ]

Nothing to do for devtools here.

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