Setup

• OS: Ubuntu 20.04.4 LTS
• mongod --version

     db version v6.0.1
     Build Info: {
       "version": "6.0.1",
       "gitVersion": "32f0f9c88dc44a2c8073a5bd47cf779d4bfdee6b",
       "openSSLVersion": "OpenSSL 1.1.1f 31 Mar 2020",
       "modules": [],
       "allocator": "tcmalloc",
       "environment":{}{
         }}{{"distmod": "ubuntu2004",
         "distarch": "x86_64",
         "target_arch": "x86_64"
{{       }}}
     }}{

• mongodb/node-mongodb-native: 4.9.1
• NodeJS: 14.19.0

Setup replica set

• Run two mongod instances:
  mongod --config /tmp/mongo/mongo1.conf
  mongod --config /tmp/mongo/mongo2.conf
• mongosh --port 27020
• configure replica set
  members: [
    { _id: 0,
      name: '127.0.0.1:27020',
      health: 1,
      state: 1,
      stateStr: 'PRIMARY',
      self: true,
      ...
    }{},
    { _id: 1,
      name: '127.0.0.1:27021',
      health: 1,
  {{    state: 2, }}
      stateStr: 'SECONDARY',
      ...
  {{  }}}
  ],

Reproduce steps

• Now mongo1 is PRIMARY, mongo2 is SECONDARY
• Run test script
  $ node rs_async.js
• All find() requests succeed
  iterations: 1311, read documents: 1311
  iterations: 2678, read documents: 2678
• run stepDown() on primary
  $ mongosh --port 27020
  test/rs_test:PRIMARY> rs.stepDown(60)
  test/rs_test:SECONDARY>
• Now mongo1 is SECONDARY, mongo2 is PRIMARY. All find() requests still succeed
• after 60 seconds mongod1 becomes PRIMARY again
• find() requests stucks
  iterations: 50262, read documents: 50262
  iterations: 50262, read documents: 50262
• each 30 seconds find() stopped by mongodb driver, next find() call stucks too
  The replica set status is OK.
  If stop the test script and run it again ('node rs_async.js'), all work.

Attachements

• configuration files for mongo1 and mongo2
• rs_async.js
• test output