while (!closed && clientRunning && !lastPacketInBlock) {
// process responses from datanodes.
try {
// read an ack from the pipeline
ack.readFields(blockReplyStream);
if (LOG.isDebugEnabled()) {
LOG.debug("DFSClient for block " + block + " " + ack);
}
long seqno = ack.getSeqno();
if (seqno == PipelineAck.HEART_BEAT.getSeqno()) {