server/src/main/java/com/orientechnologies/orient/server/distributed/ODistributedResponseManagerImpl.java
public List<String> getMissingNodes() {
    synchronousResponsesLock.lock();
    try {

      final List<String> missingNodes = new ArrayList<String>();
      for (Map.Entry<String, Object> entry : responses.entrySet())
        if (entry.getValue() == NO_RESPONSE)
          missingNodes.add(entry.getKey());
      return missingNodes;

    } finally {
      synchronousResponsesLock.unlock();
    }
  }
public List<String> getMissingNodes() {
    synchronousResponsesLock.lock();
    try {

      final List<String> missingNodes = new ArrayList<String>();
      for (Map.Entry<String, Object> entry : responses.entrySet())
        if (entry.getValue() == NO_RESPONSE)
          missingNodes.add(entry.getKey());
      return missingNodes;

    } finally {
      synchronousResponsesLock.unlock();
    }
  }
Returns the list of node names that didn't provide a response.