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  1. Core Server
  2. SERVER-26116

CSRS leaves the balancer lock unprotected briefly between leaving drain mode and the balancer acquiring it

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 3.4.0-rc4
    • Component/s: Sharding
    • Labels:
      None
    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      ALL
    • Sprint:
      Sharding 2016-10-31, Sharding 2016-11-21

      Description

      Draining mode unlocks all of the config server held distributed locks. The Balancer reacquires the {_id: "balancer"} distlock after drain mode has been left.

      Theoretically, a 3.2 Mongos could take the {_id: "balancer"} distlock in this window. It could briefly hold the distlock for a manual moveChunk, or indefinitely if auto-balancing is enabled. It could be held indefinitely if the config server is holding collection distlocks for migrations it is trying to recover after failover.

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                Updated:
                Resolved: