[HDFS-14701] Change Log Level to warn in SlotReleaser

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.3.0
• Assignee: Lisheng Sun
• Reporter: Lisheng Sun
• Created: 05/Aug/19 08:24
• Updated: 02/Oct/19 17:15
• Resolved: 08/Aug/19 20:47

Description

 if the corresponding DataNode has been stopped or restarted and DFSClient close shared memory segment，releaseShortCircuitFds API throw expection and log a ERROR Message. I think it should not be a ERROR log，and that log a warn log is more reasonable.

// @Override
public void run() {
  LOG.trace("{}: about to release {}", ShortCircuitCache.this, slot);
  final DfsClientShm shm = (DfsClientShm)slot.getShm();
  final DomainSocket shmSock = shm.getPeer().getDomainSocket();
  final String path = shmSock.getPath();
  boolean success = false;
  try (DomainSocket sock = DomainSocket.connect(path);
       DataOutputStream out = new DataOutputStream(
           new BufferedOutputStream(sock.getOutputStream()))) {
    new Sender(out).releaseShortCircuitFds(slot.getSlotId());
    DataInputStream in = new DataInputStream(sock.getInputStream());
    ReleaseShortCircuitAccessResponseProto resp =
        ReleaseShortCircuitAccessResponseProto.parseFrom(
            PBHelperClient.vintPrefixed(in));
    if (resp.getStatus() != Status.SUCCESS) {
      String error = resp.hasError() ? resp.getError() : "(unknown)";
      throw new IOException(resp.getStatus().toString() + ": " + error);
    }
    LOG.trace("{}: released {}", this, slot);
    success = true;
  } catch (IOException e) {
    LOG.error(ShortCircuitCache.this + ": failed to release " +
        "short-circuit shared memory slot " + slot + " by sending " +
        "ReleaseShortCircuitAccessRequestProto to " + path +
        ".  Closing shared memory segment.", e);
  } finally {
    if (success) {
      shmManager.freeSlot(slot);
    } else {
      shm.getEndpointShmManager().shutdown(shm);
    }
  }
}

 exception stack：

2019-08-05,15:28:03,838 ERROR [ShortCircuitCache_SlotReleaser] org.apache.hadoop.hdfs.shortcircuit.ShortCircuitCache: ShortCircuitCache(0x65849546): failed to release short-circuit shared memory slot Slot(slotIdx=62, shm=DfsClientShm(70593ef8b3d84cba3c2f0a1e81377eb1)) by sending ReleaseShortCircuitAccessRequestProto to /home/work/app/hdfs/c3micloudsrv-hdd/datanode/dn_socket.  Closing shared memory segment.

java.io.IOException: ERROR_INVALID: there is no shared memory segment registered with shmId 70593ef8b3d84cba3c2f0a1e81377eb1