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From "Gang Xie (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-12821) Block invalid IOException causes the DFSClient domain socket being disabled
Date Wed, 29 Nov 2017 07:00:00 GMT

     [ https://issues.apache.org/jira/browse/HDFS-12821?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Gang Xie updated HDFS-12821:
----------------------------
    Attachment: HDFS-12821.patch

When we receive the block invalid exception, this means it's moved to some other datanode.
We should not disable the SCR. We are suffering the performance downgrade while doing balance
on HBase cluster.

So, we need just simply skip the exception of block being invalid. Did UT about this case

> Block invalid IOException causes the DFSClient domain socket being disabled
> ---------------------------------------------------------------------------
>
>                 Key: HDFS-12821
>                 URL: https://issues.apache.org/jira/browse/HDFS-12821
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: hdfs-client
>    Affects Versions: 2.4.0, 2.6.0
>            Reporter: Gang Xie
>         Attachments: HDFS-12821.patch
>
>
> 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:
> {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;
>   }
> {code}



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