while (!responderClosed && dfsClient.clientRunning && !isLastPacketInBlock) {
// process responses from datanodes.
try {
// read an ack from the pipeline
ack.readFields(blockReplyStream);
if (DFSClient.LOG.isDebugEnabled()) {
DFSClient.LOG.debug("DFSClient " + ack);
}
long seqno = ack.getSeqno();