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  1. Core Server
  2. SERVER-17375

10% drop in throughput of rc10 vs 2.6.7 for Commands.v1.DistinctWithoutIndex

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Critical - P2
    • Resolution: Won't Fix
    • Affects Version/s: 3.0.0-rc9, 3.0.0-rc10
    • Fix Version/s: None
    • Component/s: MMAPv1
    • Labels:
    • Operating System:
      ALL
    • Steps To Reproduce:
      Hide

      /home/ec2-user/mongodb-linux-x86_64-2.6.7/bin/mongod --dbpath /data2/db --logpath /data3/logs/db/simple_commands/server.log --fork --bind_ip 127.0.0.1

      python benchrun.py -f testcases/simple_commands.js -t 1 2 4 8 12 16 20 -l SERVER-xxxx-2.6.7-mmapv0-c1 --rhost "54.191.70.12" --rport 27017 -s /home/ec2-user/mongo-perf-shell/mongo --writeCmd true --trialC
      ount 7 --trialTime 120 --testFilter \'Commands.v1.DistinctWithoutIndex\' -c 1 --dyno

      Show
      /home/ec2-user/mongodb-linux-x86_64-2.6.7/bin/mongod --dbpath /data2/db --logpath /data3/logs/db/simple_commands/server.log --fork --bind_ip 127.0.0.1 python benchrun.py -f testcases/simple_commands.js -t 1 2 4 8 12 16 20 -l SERVER-xxxx-2.6.7-mmapv0-c1 --rhost "54.191.70.12" --rport 27017 -s /home/ec2-user/mongo-perf-shell/mongo --writeCmd true --trialC ount 7 --trialTime 120 --testFilter \'Commands.v1.DistinctWithoutIndex\' -c 1 --dyno

      Description

      Problem

      Observed a 10% drop in throughput for the mongo-perf test Commands.v1.DistinctWithoutIndex. Appears to beyond normal observed variance. This is 2.6.7 vs RC9/10 MMAPV1

      2.6.7 1555.64 Stddev 33.33
      RC9 1418.79 Stddev 6.21
      RC10 1425.96 Stddev 6.46

      This appears to happen at client threads counts higher than the number of cores available to MongoDB. In the attached results, MongoDB was pinned to 8 cores, the drop appears to start after 12 client threads.

      Testcase

      tests.push( genDistinctTest( "Commands.v1.DistinctWithoutIndex", false, false ) );
      function genDistinctTest( name, index, query ) {
          var doc = { name : name,
                      tags: ['distinct','command','sanity','daily','weekly','monthly']
                    };
          if ( index ) {
              doc.pre = function( collection ) {
                  collection.drop();
                  for ( var i = 0; i < 4800; i++ ) {
                      collection.insert( { x : 1 } );
                      collection.insert( { x : 2 } );
                      collection.insert( { x : 3 } );
                  }
                  collection.ensureIndex( { x : 1 } );
              };
          }
          else {
              doc.pre = function( collection ) {
                  collection.drop();
                  for ( var i = 0; i < 4800; i++ ) {
                      collection.insert( { x : 1 } );
                      collection.insert( { x : 2 } );
                      collection.insert( { x : 3 } );
                  }
                  collection.getDB().getLastError();
              };
          }
       
          var op = { op: "command",
                     tags: ['distinct','command','sanity','daily','weekly','monthly'],
                     ns : "#B_DB",
                     command : { distinct : "#B_COLL",
                                 key : "x" } };
          if ( query )
              op.command.query = { x : 1 };
       
          doc.ops = [ op ];
       
          return doc;
      }
      

        Attachments

        1. 267.pdf
          23 kB
        2. rc10.pdf
          23 kB
        3. Screen Shot 2015-02-25 at 9.03.39 AM.png
          Screen Shot 2015-02-25 at 9.03.39 AM.png
          143 kB

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              Dates

              • Created:
                Updated:
                Resolved: