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  1. Core Server
  2. SERVER-75279

Exchange producer/consumer may get stuck if number of producers is close to number of read tickets

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    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 7.0.0-rc0
    • Affects Version/s: None
    • Component/s: None
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    • Query Optimization
    • Fully Compatible
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      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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      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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      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.

            Assignee:
            svilen.mihaylov@mongodb.com Svilen Mihaylov (Inactive)
            Reporter:
            gregory.noma@mongodb.com Gregory Noma
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              Created:
              Updated:
              Resolved: