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  1. Core Server
  2. SERVER-23605

100% CPU usage in update one field in one document

    • Type: Icon: Bug Bug
    • Resolution: Done
    • Priority: Icon: Critical - P2 Critical - P2
    • None
    • Affects Version/s: 3.2.3
    • Component/s: WiredTiger, Write Ops
    • Environment:
      Azure VM D2 size
    • ALL
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      Fill collection with more than 400.000 documents with many text data (5KB) in some properties. Try to update one field at some object.

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      Fill collection with more than 400.000 documents with many text data (5KB) in some properties. Try to update one field at some object.

      I have a simple social crawler written in C# for testing MongoDB performance and decide - use it in another projects.
      It collected 750.000 documents in collection Post.
      Document post have "IsApproved" property that I want to update.

      Posts collection have _id index and

      { "SiteId" : 1, "IsApproved" : -1, "Date" : -1 }

      I make project to find one with

      {Id, IsApproved}

      and UpdateOne with !Approved (see screenshot).

      Inserting documents fine and my Azure VM (D2 (2 cores Xeon with SSD) CPU costs about 2-8 percent.
      But if I press approve button in my crawler - it "think" 3-5 seconds and costs 40% CPU.
      If i press Approve button multiple times without pause - it kill my server and CPU load at 99% for each update time (see screenshot).
      Don't say than i need be toggle boolean property with XOR command - i approximate it to other updates and i worry.

      How I will use database, that only one update costs so many CPU times ?
      It's not normal behaviour. Maybe that index rebuild ?

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            Assignee:
            kelsey.schubert@mongodb.com Kelsey Schubert
            Reporter:
            zoxexivo@gmail.com Ivan Artemov
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              Created:
              Updated:
              Resolved: