[jira] [Created] (HDFS-13121) NPE when request file descriptors when SC read

["Gang Xie (JIRA)" <ji...@apache.org>]

Gang Xie created HDFS-13121:
-------------------------------

             Summary: NPE when request file descriptors when SC read
                 Key: HDFS-13121
                 URL: https://issues.apache.org/jira/browse/HDFS-13121
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: hdfs-client
    Affects Versions: 3.0.0
            Reporter: Gang Xie


Recently, we hit an issue that the DFSClient throws NPE. The case is that, the app process exceeds the limit of the max open file. In the case, the libhadoop never throw and exception but return null to the request of fds. But requestFileDescriptors use the returned fds directly without any check and then NPE. 

 

We need add a sanity check here of null pointer.

 

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,
 failureInjector.getSupportsReceiptVerification());
 DataInputStream in = new DataInputStream(peer.getInputStream());
 BlockOpResponseProto resp = BlockOpResponseProto.parseFrom(
 PBHelperClient.vintPrefixed(in));
 DomainSocket sock = peer.getDomainSocket();
 failureInjector.injectRequestFileDescriptorsFailure();
 switch (resp.getStatus()) {
 case SUCCESS:
 byte buf[] = new byte[1];
 FileInputStream[] fis = new FileInputStream[2];
 {color:#d04437}sock.recvFileInputStreams(fis, buf, 0, buf.length);{color}
 ShortCircuitReplica replica = null;
 try {
 ExtendedBlockId key =
 new ExtendedBlockId(block.getBlockId(), block.getBlockPoolId());
 if (buf[0] == USE_RECEIPT_VERIFICATION.getNumber()) {
 LOG.trace("Sending receipt verification byte for slot {}", slot);
 sock.getOutputStream().write(0);
 }
 {color:#d04437}replica = new ShortCircuitReplica(key, fis[0], fis[1], cache,{color}
{color:#d04437} Time.monotonicNow(), slot);{color}



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