[SERVER-52732] Uptime reporter disables autosplit during ShardingTest initialization Created: 10/Nov/20  Updated: 29/Oct/23  Resolved: 10/Dec/20

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: 4.2.11
Fix Version/s: 4.2.12

Type: Bug Priority: Minor - P4
Reporter: Pierlauro Sciarelli Assignee: Pierlauro Sciarelli
Resolution: Fixed Votes: 0
Labels: sharding-wfbf-day
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Depends
Backwards Compatibility: Fully Compatible
Operating System: ALL
Participants:
Linked BF Score: 13

 Description   

Starting from v4.2, disabling the balancer is also resulting in disabling the autosplitter.

When a ShardingTest is initialized with enableAutoSplit: true, the balancer is disabled and autosplitter is enabled.

Those 2 operations are not happening atomically, so there is a small window in which both components are disabled. This makes it possible for the v4.0 ShardingUptimeReporter to kick in and assume - until next refresh in 10 seconds - that autospliting is disabled.

When that happens, autosplit.js fails in the sharding_last_stable_mongos_and_mixed_shards suite between v4.2 and v4.0 .

 

Both v4.2 and v4.0 are flagged as affected, but the fix should target just one version depending on how it will be implemented: fixing the test in v4.2 (more likely) or the code in v4.0.



 Comments   
Comment by Githook User [ 10/Dec/20 ]

Author:

{'name': 'Pierlauro Sciarelli', 'email': 'pierlauro.sciarelli@mongodb.com', 'username': 'pierlauro'}

Message: SERVER-52732 Uptime reporter disables autosplit during ShardingTest initialization
Branch: v4.2
https://github.com/mongodb/mongo/commit/09790b368a2e0b80f29bb06d33975bb31c00213b

Comment by Pierlauro Sciarelli [ 12/Nov/20 ]

Could be solved by backporting the disableShardingUptimeReporterPeriodicThread failpoint to v4.0.

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