[SERVER-47543] Hedge reads request hang when hedge read finishes first with MaxTimeMSExpired error Created: 14/Apr/20  Updated: 29/Oct/23  Resolved: 22/Apr/20

Status: Closed
Project: Core Server
Component/s: Internal Code
Affects Version/s: 4.4.0-rc0
Fix Version/s: 4.4.0-rc3, 4.7.0

Type: Bug Priority: Major - P3
Reporter: Misha Tyulenev Assignee: Misha Tyulenev
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Backwards Compatibility: Fully Compatible
Operating System: ALL
Backport Requested:
v4.4
Steps To Reproduce:

The failure is intermittent, appeared several times during testing.
It appeared when a count or find request was submitted with a hedge read, then the primary request retried on StaleConfig error.

Sprint: Service arch 2020-04-20, Service arch 2020-05-04
Participants:

 Description   

This is an intermittent failure that causes a read command to hang indefinitely when hedge reads are enabled and permitted i.e. as with readPreference mode nearest
The root cause is that if a hedge read that expired with MaxTimeMSExpired error before the original request will be ignored but as it triggers the finish line the follow-up response will be ignored as well.



 Comments   
Comment by Githook User [ 23/Apr/20 ]

Author:

{'name': 'Misha Tyulenev', 'email': 'misha@mongodb.com', 'username': 'mikety'}

Message: SERVER-47543 fix hang when hedge read finishes first with MaxTimeMSExpired error

(cherry picked from commit 2dafa910d5faf63e6ab4aef0e2ecbc9712878c94)
Branch: v4.4
https://github.com/mongodb/mongo/commit/0c920f9abcff3d255e8378b1774e6b9efd1f7dc4

Comment by Githook User [ 22/Apr/20 ]

Author:

{'name': 'Misha Tyulenev', 'email': 'misha@mongodb.com', 'username': 'mikety'}

Message: SERVER-47543 fix hang when hedge read finishes first with MaxTimeMSExpired error
Branch: master
https://github.com/mongodb/mongo/commit/2dafa910d5faf63e6ab4aef0e2ecbc9712878c94

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