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HDFS-15925. The lack of packet-level mirrorError state synchronization in BlockReceiver can cause the HDFS client to hang #2821

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HDFS-15925. The lack of packet-level mirrorError state synchronization in BlockReceiver can cause the HDFS client to hang #2821

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21 changes: 17 additions & 4 deletions ...oject/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Queue;
import java.util.concurrent.Semaphore;
import java.util.concurrent.atomic.AtomicLong;
import java.util.zip.Checksum;

Expand Down Expand Up @@ -532,7 +533,7 @@ private boolean shouldVerifyChecksum() {
* Receives and processes a packet. It can contain many chunks.
* returns the number of data bytes that the packet has.
*/
private int receivePacket() throws IOException {
private int receivePacket(final Semaphore ackSema) throws IOException {
// read the next packet
packetReceiver.receiveNextPacket(in);

Expand Down Expand Up @@ -616,6 +617,9 @@ private int receivePacket() throws IOException {
handleMirrorOutError(e);
}
}
if (ackSema != null) {
ackSema.release();
}

ByteBuffer dataBuf = packetReceiver.getDataSlice();
ByteBuffer checksumBuf = packetReceiver.getChecksumSlice();
Expand Down Expand Up @@ -984,13 +988,15 @@ void receiveBlock(
this.isReplaceBlock = isReplaceBlock;

try {
Semaphore ackSema = null;
if (isClient && !isTransfer) {
ackSema = new Semaphore(0);
responder = new Daemon(datanode.threadGroup,
new PacketResponder(replyOut, mirrIn, downstreams));
new PacketResponder(replyOut, mirrIn, downstreams, ackSema));
responder.start(); // start thread to processes responses
}

while (receivePacket() >= 0) { /* Receive until the last packet */ }
while (receivePacket(ackSema) >= 0) { /* Receive until the last packet */ }

// wait for all outstanding packet responses. And then
// indicate responder to gracefully shutdown.
Expand Down Expand Up @@ -1246,16 +1252,20 @@ class PacketResponder implements Runnable, Closeable {
/** for log and error messages */
private final String myString;
private boolean sending = false;
/** for synchronization with BlockReceiver */
private final Semaphore ackSema;

@Override
public String toString() {
return myString;
}

PacketResponder(final DataOutputStream upstreamOut,
final DataInputStream downstreamIn, final DatanodeInfo[] downstreams) {
final DataInputStream downstreamIn, final DatanodeInfo[] downstreams,
final Semaphore ackSema) {
this.downstreamIn = downstreamIn;
this.upstreamOut = upstreamOut;
this.ackSema = ackSema;

this.type = downstreams == null? PacketResponderType.NON_PIPELINE
: downstreams.length == 0? PacketResponderType.LAST_IN_PIPELINE
Expand Down Expand Up @@ -1395,6 +1405,9 @@ public void run() {
long seqno = PipelineAck.UNKOWN_SEQNO;
long ackRecvNanoTime = 0;
try {
if (ackSema != null) {
ackSema.acquire();
}
if (type != PacketResponderType.LAST_IN_PIPELINE && !mirrorError) {
DataNodeFaultInjector.get().failPipeline(replicaInfo, mirrorAddr);
// read an ack from downstream datanode
Expand Down