Improve connection pool scaling

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    • Type: Improvement
    • Resolution: Done
    • Priority: Major - P3
    • 5.3.0
    • Affects Version/s: None
    • Component/s: Connection Management
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    • Fully Compatible
    • Java Drivers
    • Needed
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      Let's mention in what's new that we removed explicit fairness from our connection pool implementation. We expect this to allow for better throughput when MongoClient is used by many application threads, at the potential cost of increased tail latency.

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      Let's mention in what's new that we removed explicit fairness from our connection pool implementation. We expect this to allow for better throughput when MongoClient is used by many application threads, at the potential cost of increased tail latency.
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      A modified YCSB 100 ping workload without ssl cannot scale vertically past 300 kops/s no matter how many threads you specify in YCSB. Offcpu flamegraph shows unsafe_park mutex

      Unsafe_Park is being called inside ConcurrentPool.get() and ConcurrentPool.release() where it calls lockInterruptiblyUnfair(). I believe this is the culprit.

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        3. java_merged_off.svg
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        4. oncpu.html
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            Assignee:
            Valentin Kavalenka
            Reporter:
            Daniel Hill
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              Created:
              Updated:
              Resolved: