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  1. Node.js Driver
  2. NODE-2710

Replica set don’t make election if insertion interval is less than 501 ms

    • Type: Icon: Bug Bug
    • Resolution: Duplicate
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: 3.5.9
    • Component/s: None

      • I'm Using Mongodb Native driver 3.6
      • configured PSA replicaSet (on the same machine) and this is its configuration parameters

       

       

      rs0:PRIMARY> rs.config()
      {
       "_id" : "rs0",
       "version" : 319263,
       "protocolVersion" : NumberLong(1),
       "writeConcernMajorityJournalDefault" : true,
       "members" : [
       {
       "_id" : 2,
       "host" : "192.168.45.77:27017",
       "arbiterOnly" : false,
       "buildIndexes" : true,
       "hidden" : false,
       "priority" : 5,
       "tags" : {
      },
       "slaveDelay" : NumberLong(0),
       "votes" : 1
       },
       {
       "_id" : 4,
       "host" : "192.168.45.77:27015",
       "arbiterOnly" : false,
       "buildIndexes" : true,
       "hidden" : false,
       "priority" : 1,
       "tags" : {
      },
       "slaveDelay" : NumberLong(0),
       "votes" : 1
       },
       {
       "_id" : 5,
       "host" : "192.168.45.77:27020",
       "arbiterOnly" : true,
       "buildIndexes" : true,
       "hidden" : false,
       "priority" : 0,
       "tags" : {
      },
       "slaveDelay" : NumberLong(0),
       "votes" : 1
       }
       ],
       "settings" : {
       "chainingAllowed" : true,
       "heartbeatIntervalMillis" : 2000,
       "heartbeatTimeoutSecs" : 10,
       "electionTimeoutMillis" : 5000,
       "catchUpTimeoutMillis" : -1,
       "catchUpTakeoverDelayMillis" : 30000,
       "getLastErrorModes" : {
      },
       "getLastErrorDefaults" : {
       "w" : 1,
       "wtimeout" : 0
       },
       "replicaSetId" : ObjectId("5ed8d7489ff195f6b8ff442c")
       }
      }
      

      i tried to insert into the database with interval and intentionaly stop the primary server to confirm election is done and a new primary is selected

       

      const {ObjectID, MongoClient } = require('mongodb')
      client = new MongoClient('mongodb://localhost:27017,localhost:27015,localhost:27020/logs?replicaSet=rs0', {
       useUnifiedTopology: true,
       serverSelectionTimeoutMS: 15000
      })
      client.on('topologyDescriptionChanged', event => {
       console.log(event.newDescription.type)
      })
      let db
      client.connect((err, client) => {
       if (err) {
       return console.log('error inside connection', err)
       } 
       
       db = client
      })
      setInterval(() => {
       db
       .db()
       .collection('logs')
       .insertOne({
       _id: new ObjectID(),
       foo: 'bar'
       })
       .then(result => {
       console.log(result.insertedId)
       })
       .catch(err => {
       console.log(`err`, err)
       })
      }, 500)
      
      • There are two scenarios

      1- interval time is more than 500 ms

      • `topologyDescriptionChanged` event is fired more than one time
      • in this case election is made normally and everything is ok

      2- interval time is less than 501 ms

      • `topologyDescriptionChanged` event is fired once with type ReplicaSetNoPrimary and after it reaches serverSelectionTimeoutMS it throws MongoServerSelectionError: not master which means no election is made

      .
      .

      also i tried the same operation with python (pymongo) and everything worked fine with interval 100 ms

      from pymongo import MongoClient
      from time import sleep
      
      
      import threading
      
      def set_interval(func, sec):
          def func_wrapper():
              set_interval(func, sec)
              func()
          t = threading.Timer(sec, func_wrapper)
          t.start()
          return t
      
      
      c = MongoClient('mongodb://localhost:27017,localhost:27015,localhost:27020/?replicaSet=rs0').test
      
      def insert():
          z = c.test.insert_one({"x": 1})
          print(z.inserted_id)
      
      
      set_interval(insert,.1)
      

            Assignee:
            matt.broadstone@mongodb.com Matt Broadstone
            Reporter:
            ahm2015ed@gmail.com ahmed naser
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              Created:
              Updated:
              Resolved: