public boolean notMoreExtractorNeededToBeAssigned() {
    return matcher.getRegisterCount() == 0;
  }
The {@link DisruptorQueue} is used to assign the event to the extractor.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/extractor/dataregion/realtime/assigner/PipeDataRegionAssigner.java