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  1. Core Server
  2. SERVER-21805

RAM usage - slow down server

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    • Icon: Bug Bug
    • Resolution: Done
    • Icon: Major - P3 Major - P3
    • None
    • 3.0.3
    • WiredTiger
    • None
    • ALL
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      1. RS with WT
      2. Collection with 500 GB data
      3. Loop over the collection (we use PHP)

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      1. RS with WT 2. Collection with 500 GB data 3. Loop over the collection (we use PHP)

    Description

      We have a replica set with one secondary and one arbiter (each on a different server) and moved from MMapv1 to WiredTiger. Primary and Secondary each have 32 GB. We have now a process where we read each document once. The mongod process uses all of the 32 GB RAM and the server is very slow.
      Attached you will find our serverStatus: wt cache size is 16 GB, tcmalloc size is 26 GB.
      So the question for us is, why WT uses all of the 32 GB and swaps now and how can we fix that. Also, if we upgrade to a new version, we see in the jira tasks, that there are a lot of problems with memory leaks together with WT. So what recommendation do you have.

      free -m output:
      total used free shared buffers cached
      Mem: 32136 31727 409 0 9 2899
      -/+ buffers/cache: 28819 3317
      Swap: 49152 609 48543

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            Unassigned Unassigned
            k9908600@gmx.at Niti Test
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