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  1. Core Server
  2. SERVER-31573

WT table not dropped on primary after collection is dropped

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Duplicate
    • Affects Version/s: 3.6.0-rc0
    • Fix Version/s: None
    • Component/s: WiredTiger
    • Labels:
      None
    • Backwards Compatibility:
      Fully Compatible
    • Operating System:
      ALL

      Description

      In a replica set

      • create a collection by inserting a document
      • restart the replica set
      • then drop the collection or database

      On the primary the corresponding WT tables may not be dropped, and the .wt file will remain.

      The following script reproduces the problem about half the time. The script ends with a loop that waits for the .wt file for the collection to disappear from all members; the problem is reproduced if the loop at the end never terminates and the offending file is associated with the member that was elected as primary. Since the script also reliably reproduces SERVER-31101, you have to check whether the .wt file associated with the primary remains in order to determine whether this issue has been reproduced. The script prints replica set status before going into the wait loop to help with this.

      Note also that the script uses killall -w, so as written will work on Linux but not OSX.

      function repro {
       
          db=/ssd/db # change this as required
          uri='mongodb://localhost:27017/test?replicaSet=rs'
       
          function clean {
              killall -9 -w mongod
              rm -rf $db
          }
              
          function start {
              for i in 0 1 2; do 
                  mkdir -p $db/r$i
                  mongod --dbpath $db/r$i --logpath ./r$i.log --port 27${i}17 --replSet rs --fork
              done
          }
       
          function stop {
              killall -w mongod
          }
       
          function initiate {
              mongo --quiet --eval '
                  rs.initiate({
                      _id: "rs",
                       members: [
                           {_id: 0, host: "localhost:27017"},
                           {_id: 1, host: "localhost:27117"},
                           {_id: 2, host: "localhost:27217"}
                      ]
                  })
              '
          }
       
          # get collection filename for port $1
          function fn {
              mongo --quiet --port $1 --eval '
                  rs.slaveOk()
                  print(db.runCommand({collStats: "c"}).wiredTiger.uri.substr(17))
              '
          }
       
          # start new replica set
          clean; start; initiate
       
          # create test.c, wait for replication
          mongo --quiet $uri --eval 'db.c.insert({})'
          sleep 5
       
          # note collection filenames on each member
          fn0=$db/r0/$(fn 27017).wt
          fn1=$db/r1/$(fn 27117).wt
          fn2=$db/r2/$(fn 27217).wt
          
          # restart
          stop; start
       
          # drop collection
          sleep 5
          mongo --quiet $uri --eval 'print("drop:", db.c.drop())'
       
          # print member status so we can tell which is offending member
          sleep 5
          mongo --quiet $uri --eval '
              members = rs.status().members
              for (var i in members)
                  print(members[i].name, members[i].stateStr)
          '
       
          # wait for all files to disappear
          # problem is reproduced if this waits forever
          while [[ -e $fn0 || -e $fn1 || -e $fn2 ]]; do
              ls -l $fn0 $fn1 $fn2
              sleep 1
          done
      }
      

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                • Created:
                  Updated:
                  Resolved: