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  1. Core Server
  2. SERVER-46121

mongos crashes with invariant error after changing taskExecutorPoolSize

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Critical - P2
    • Resolution: Fixed
    • Affects Version/s: 4.2.3
    • Fix Version/s: 4.2.4, 4.3.4
    • Component/s: Sharding
    • Labels:
    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      ALL
    • Backport Requested:
      v4.2
    • Steps To Reproduce:
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      OS: current Ubuntu 18.04

      MongoDB - Version: 4.2.3

      fcv: 4.0

      number of cfg-Servers: 3

      number of shards: 4 (PSA - Replicasets)

      number of connected mongos: 3

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      OS: current Ubuntu 18.04 MongoDB - Version: 4.2.3 fcv: 4.0 number of cfg-Servers: 3 number of shards: 4 (PSA - Replicasets) number of connected mongos: 3
    • Sprint:
      Service Arch 2020-02-24, Service Arch 2020-03-09
    • Case:

      Description

      Hi, we are running a sharded cluster on Ubuntu 18.04. (amd64) it was recently upgraded from version 4.0.x to 4.2.3. The cluster's fcv is still set to 4.0.

      After facing some performance issues we increased the taskExecutorPoolSize on the mongos to match the number of cores in the servers. This gave us a huge boost in query performance using 4.0.x. After the Upgrade the mongos process crashes after a few seconds using the same configuration. 

      mongos.conf tmp.log

      Removing the taskExecutorPoolSize entry solves the issue, but gives us poor query performance. (4 times slower on a quad core system).

      We also tried a clean install in a test-environment on the same OS and DB version, with an empty Database and got the same error.

        Attachments

        1. mongos.conf
          0.4 kB
        2. tmp.log
          0.2 kB

          Activity

            People

            Assignee:
            ben.caimano Benjamin Caimano
            Reporter:
            toni.papp@gmail.com Anton Papp
            Participants:
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              Dates

              Created:
              Updated:
              Resolved: