[SERVER-75279] Exchange producer/consumer may get stuck if number of producers is close to number of read tickets Created: 24/Mar/23 Updated: 29/Oct/23 Resolved: 29/Mar/23 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | 7.0.0-rc0 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Gregory Noma | Assignee: | Svilen Mihaylov (Inactive) |
| Resolution: | Fixed | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Assigned Teams: |
Query Optimization
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| Backwards Compatibility: | Fully Compatible | ||||||||||||
| Operating System: | ALL | ||||||||||||
| Steps To Reproduce: | Run jstests/cqf_parallel/index.js or jstests/cqf_parallel/groupby.js with the storageEngineConcurrencyAdjustmentAlgorithm server parameter set to "" and the storageEngineConcurrentReadTransactions server parameter set to either 5 or 6. |
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| Participants: | |||||||||||||
| Linked BF Score: | 149 | ||||||||||||
| Description |
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When we spawn exchange producer threads, each one takes a global IS lock (and thus also takes a read ticket). If the number of read tickets is less than, equal to, or just slightly above the number of producers we're creating, we may get stuck; some of the producers will queue for a read ticket and block at the global lock acquisition forever. |
| Comments |
| Comment by Githook User [ 29/Mar/23 ] |
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Author: {'name': 'Svilen Mihaylov', 'email': 'svilen.mihaylov@mongodb.com', 'username': 'svilen-mihaylov'}Message: |
| Comment by Alya Berciu [ 28/Mar/23 ] |
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david.storch@mongodb.com I created a dedicated ticket ( |
| Comment by Alya Berciu [ 27/Mar/23 ] |
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Reassigning to QE, since this appears to happen in SBE code. |