Why TWX Platform could not receive/queue all value streams updated by edges?

We made one edge update a temperature property increased by 1 every 5 secs. If 300k ~ 400k edges update logged temperature properties(value streams) every 5 secs concurrently, the ThingWorx Platform(TWX) could only receive/queue 85% ~ 90% of properties. When the edges' connections are established stably, We observed the 'totalWritesQueued' value of Value Stream Substem every 5 secs and computed its minus, then divided this minus by the amount of edges.

My question is, why the TWX couldn't handle 100% of properties when  more than 300k edges update properties concurrently?

+ TWX System Resource:

  - CPU E5-2650 v3 @ 2.30GHz with 10 cores * HT * 2-way

  - CPU usage: less than 50%

  - Total Memory: 128GB

  - JVM Memory: 96GB

+ TWX Subsystem Configuration:

  - Default except:

    > Value Stream Subsystem:

      ' maximumBlockSize: 50,000

      ' maximumQueueSize: 10, 000, 000

      ' maximumWaitTime: 1000

      ' numberOfProcessingThreads: 80

+ Logs:

  - Tomcat:

    com.thingworx.exceptions.CouldNotConnectException: 172.21.128.30-temp13270 is not connected

    java.util.concurrent.TimeoutException: Timed out APIRequestMessage [requestId: 1398634, endpointId: -1, sessionId: -1, method: POST, entityName:

    172.21.128.30-temp11300, characteristic: Services, target: NotifyPropertyUpdate]

  - TWX:

    [L: ERROR] [O: c.t.p.p.BatchStreamEntryProcessor] [I: ] [U: SuperUser] [S: ] [T: pool-8-thread-10] Error executing batch

    [L: WARN] [O: c.t.s.s.w.WSCommunicationsSubsystem] [I: ] [U: ] [S: ] [T: WsCommunication-151] Could not dispatch async service request [NotifyPropertyUpdate] :

      Timed out APIRequestMessage [requestId: 1405707, endpointId: -1, sessionId: -1, method: POST, entityName: 172.18.142.102-temp540, characteristic: Services,

      target:NotifyPropertyUpdate]

    [L: WARN] [O: c.t.c.s.e.DispatchingServerEndpoint] [I: ] [U: ] [S: ] [T: http-nio-8080-exec-68] NULL MessageSynchronizationContext! Request either timed-out waiting

      for this response, or it was received by mistake: ResponseMessage [requestId: 1401202, endpointId: 175200, sessionId: 1406274, code: STATUS_SUCCESS,

      multipart: false, packet #: 0, total packets: 0]

+ QueryPropertyHistory for One Thing: NOT CONTINUOUS