[HDFS-12821] Block invalid IOException causes the DFSClient domain socket being disabled

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 2.4.0, 2.6.0
• Component/s: hdfs-client
• Assignee: Unassigned
• Reporter: Gang Xie
• Created: 16/Nov/17 02:15
• Updated: 29/Nov/17 06:59
• Resolved: 16/Nov/17 08:11

Description

We use HDFS2.4 & 2.6, and recently hit a issue that DFSClient domain socket is disabled when datanode throw block invalid exception.

The block is invalidated for some reason on datanote and it's OK. Then DFSClient tries to access this block on this datanode via domain socket. This triggers a IOExcetion. On DFSClient side, when get a IOExcetion and error code 'ERROR', it disables the domain socket and fails back to TCP. and the worst is that it seems never recover the socket.

I think this is a defect and with such "block invalid" exception, we should not disable the domain socket because the is nothing wrong about the domain socket service.

And thoughts?

The code:

private ShortCircuitReplicaInfo requestFileDescriptors(DomainPeer peer,
        Slot slot) throws IOException {
  ShortCircuitCache cache = clientContext.getShortCircuitCache();
  final DataOutputStream out =
      new DataOutputStream(new BufferedOutputStream(peer.getOutputStream()));
  SlotId slotId = slot == null ? null : slot.getSlotId();
  new Sender(out).requestShortCircuitFds(block, token, slotId, 1);
  DataInputStream in = new DataInputStream(peer.getInputStream());
  BlockOpResponseProto resp = BlockOpResponseProto.parseFrom(
      PBHelper.vintPrefixed(in));
  DomainSocket sock = peer.getDomainSocket();
  switch (resp.getStatus()) {
  case SUCCESS:
    byte buf[] = new byte[1];
    FileInputStream fis[] = new FileInputStream[2];
    sock.recvFileInputStreams(fis, buf, 0, buf.length);
    ShortCircuitReplica replica = null;
    try {
      ExtendedBlockId key =
          new ExtendedBlockId(block.getBlockId(), block.getBlockPoolId());
      replica = new ShortCircuitReplica(key, fis[0], fis[1], cache,
          Time.monotonicNow(), slot);
    } catch (IOException e) {
      // This indicates an error reading from disk, or a format error.  Since
      // it's not a socket communication problem, we return null rather than
      // throwing an exception.
      LOG.warn(this + ": error creating ShortCircuitReplica.", e);
      return null;
    } finally {
      if (replica == null) {
        IOUtils.cleanup(DFSClient.LOG, fis[0], fis[1]);
      }
    }
    return new ShortCircuitReplicaInfo(replica);
  case ERROR_UNSUPPORTED:
    if (!resp.hasShortCircuitAccessVersion()) {
      LOG.warn("short-circuit read access is disabled for " +
          "DataNode " + datanode + ".  reason: " + resp.getMessage());
      clientContext.getDomainSocketFactory()
          .disableShortCircuitForPath(pathInfo.getPath());
    } else {
      LOG.warn("short-circuit read access for the file " +
          fileName + " is disabled for DataNode " + datanode +
          ".  reason: " + resp.getMessage());
    }
    return null;
  case ERROR_ACCESS_TOKEN:
    String msg = "access control error while " +
        "attempting to set up short-circuit access to " +
        fileName + resp.getMessage();
    if (LOG.isDebugEnabled()) {
      LOG.debug(this + ":" + msg);
    }
    return new ShortCircuitReplicaInfo(new InvalidToken(msg));
  default:
    LOG.warn(this + ": unknown response code " + resp.getStatus() +
        " while attempting to set up short-circuit access. " +
        resp.getMessage());
    clientContext.getDomainSocketFactory()
        .disableShortCircuitForPath(pathInfo.getPath());                <<<<<<=====
    return null;
  }

Issue Links

• duplicates: HDFS-12528 Add an option to not disable short-circuit reads on failures