[SERVER-53639] Add MongoS server status metrics to track how often a cursor has more than 1 batch Created: 07/Jan/21  Updated: 29/Oct/23  Resolved: 22/Jan/21

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 4.9.0-alpha3

Type: Task Priority: Major - P3
Reporter: Vishnu Kaushik Assignee: Vishnu Kaushik
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
Documented
is documented by DOCS-14152 Investigate changes in SERVER-53639: ... Closed
Related
related to SERVER-49867 Add server status metrics to track ho... Closed
Backwards Compatibility: Fully Compatible
Sprint: Repl 2021-01-25
Participants:

 Description   

MongoS starts off by issuing a query of batch size 0. Thus, cursors by MongoS will always call a getMore, and therefore, the server status metric which tracks how many cursors return more than one batch will have an artificially inflated value.

The solution - we will be counting the number of cursors that call getMore on MongoS. Thus we will know when to ignore the artificially inflated value.



 Comments   
Comment by Githook User [ 22/Jan/21 ]

Author:

{'name': 'Vishnu Kaushik', 'email': 'vishnu.kaushik@mongodb.com', 'username': 'kauboy26'}

Message: SERVER-53639 Add MongoS server status metrics to track how often a cursor has more than 1 batch
Branch: master
https://github.com/mongodb/mongo/commit/2c3fa7426c27f5a93d060fce0384ae11c471a319

Comment by Lingzhi Deng [ 11/Jan/21 ]

I think this is to track the mongoS portion of SERVER-49867. We will provide the same metrics as SERVER-49867 on mongoS so that the metrics from mongoS will be accurate.

Comment by Bruce Lucas (Inactive) [ 08/Jan/21 ]

I'm not sure what "handled" means - wouldn't we still want to record all getmores, even if of size 0?

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