public void updateSafelyDeletedSearchIndex() {
      // update safely deleted search index to delete outdated info,
      // indicating that insert nodes whose search index are before this value can be deleted
      // safely.
      //
      // Use minFlushedSyncIndex here to reserve the WAL which are not flushed and support kill -9.
      reader.setSafelyDeletedSearchIndex(impl.getMinFlushedSyncIndex());
      // notify
      if (impl.unblockWrite()) {
        impl.signal();
      }
    }
try to remove a request from queue with memory control.
iotdb-core/consensus/src/main/java/org/apache/iotdb/consensus/iot/logdispatcher/LogDispatcher.java