[SERVER-57230] mongos doesn't distribute secondary reads evenly on v4.4 or above Created: 26/May/21 Updated: 31/May/22 Resolved: 31/May/22 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | 4.4.0 |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Tyler Seip (Inactive) | Assignee: | Vojislav Stojkovic |
| Resolution: | Duplicate | Votes: | 2 |
| Labels: | servicearch-q4-2021, servicearch-wfbf-day | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Operating System: | ALL | ||||||||||||||||||||||||
| Sprint: | Service Arch 2021-06-28, Service Arch 2021-07-12, Service Arch 2021-08-09, Service Arch 2021-08-23, Service Arch 2021-10-04, Service Arch 2022-1-24, Service Arch 2022-2-07, Service Arch 2022-2-21, Service Arch 2022-03-07, Service Arch 2022-03-21, Service Arch 2022-04-04 | ||||||||||||||||||||||||
| Participants: | |||||||||||||||||||||||||
| Case: | (copied to CRM) | ||||||||||||||||||||||||
| Story Points: | 5 | ||||||||||||||||||||||||
| Description |
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In v4.2, mongos correctly balanced outgoing read requests to secondary nodes by randomizing the connection order when we issued requests here. In v4.4, the introduction of either hedged reads, opportunistic reads, or changes to ConnectionPool have made it such that one of these connections now consistently resolves first, effectively starving one of the secondaries of any reads and unbalancing our read requests. In this ticket, create a unit or integration test to capture this behavior and fix it. |
| Comments |
| Comment by Vojislav Stojkovic [ 31/May/22 ] |
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Fixed by |
| Comment by Lauren Lewis (Inactive) [ 28/Oct/21 ] |
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De-prioritized, not currently working. Will revisit & keeping assigned to tyler.seip |