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  1. MongoDB Database Tools
  2. TOOLS-1499

Use of mgo sessions may replay with more connections than recorded

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    Details

    • Type: Task
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Duplicate
    • Affects Version/s: 3.4.0-rc0
    • Fix Version/s: None
    • Component/s: mongoreplay
    • Labels:
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      Description

      • A-B: recorded workload does some inserts on 8 connections and then a collection scan on a single connection
      • C-D: playback creates up to 45 connections.

      However mongoreplay reported using only 11 connections:

      2016/10/19 15:01:10 Doing playback at 1.00x speed
      2016/10/19 15:01:10 Preprocessing file
      2016/10/19 15:01:11 Preprocess complete
      2016/10/19 15:02:02 8150 ops played back in 51.156882773s seconds over 11 connections
      2016/10/19 15:02:02 Doing playback at 1.00x speed
      2016/10/19 15:02:02 Preprocessing file
      2016/10/19 15:02:02 Preprocess complete
      2016/10/19 15:02:52 8150 ops played back in 49.503066395s seconds over 11 connections
      

      About half of the 45 connections were created during the second spurious playback (TOOLS-1497) so presumably fixing that would cut the number of connections by about half, but this still leaves mongoreplay using 2-3x as many connections as the original workload. This is potentially an issue for workloads with a large number of connections.

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              Assignee:
              backlog-server-tools Backlog - Server Tools Team
              Reporter:
              bruce.lucas Bruce Lucas
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                Created:
                Updated:
                Resolved: