public synchronized OptionalLong getMinFlushedSyncIndex() {
    return threads.stream().mapToLong(LogDispatcherThread::getLastFlushedSyncIndex).min();
  }
Manage all asynchronous replication threads and corresponding async clients.
iotdb-core/consensus/src/main/java/org/apache/iotdb/consensus/iot/logdispatcher/LogDispatcher.java