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HDFS-4200. Reduce the size of synchronized sections in PacketResponder. Contributed by Suresh Srinivas. 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1413826 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Suresh Srinivas 2012-11-26 20:47:58 +00:00
parent 68bc61ab5c
commit 7e56bfe405
2 changed files with 179 additions and 153 deletions
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3
hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
View File

@ -167,6 +167,9 @@ Trunk (Unreleased)
HDFS-4215. Remove locking from addToParent(..) since it is used in image
loading, and add INode.isFile(). (szetszwo)
HDFS-4200. Reduce the size of synchronized sections in PacketResponder.
(suresh)
OPTIMIZATIONS
BUG FIXES

201
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java
View File

@ -638,10 +638,7 @@ void receiveBlock(
responder.start(); // start thread to processes responses
}
/*
* Receive until the last packet.
*/
while (receivePacket() >= 0) {}
while (receivePacket() >= 0) { /* Receive until the last packet */ }
// wait for all outstanding packet responses. And then
// indicate responder to gracefully shutdown.
@ -724,7 +721,7 @@ private void adjustCrcFilePosition() throws IOException {
static private long checksum2long(byte[] checksum) {
long crc = 0L;
for(int i=0; i<checksum.length; i++) {
crc |= (0xffL&(long)checksum[i])<<((checksum.length-i-1)*8);
crc |= (0xffL&checksum[i])<<((checksum.length-i-1)*8);
}
return crc;
}
@ -783,24 +780,23 @@ private static enum PacketResponderType {
NON_PIPELINE, LAST_IN_PIPELINE, HAS_DOWNSTREAM_IN_PIPELINE
}
private static Status[] MIRROR_ERROR_STATUS = {Status.SUCCESS, Status.ERROR};
/**
* Processed responses from downstream datanodes in the pipeline
* and sends back replies to the originator.
*/
class PacketResponder implements Runnable, Closeable {
/** queue for packets waiting for ack */
/** queue for packets waiting for ack - synchronization using monitor lock */
private final LinkedList<Packet> ackQueue = new LinkedList<Packet>();
/** the thread that spawns this responder */
private final Thread receiverThread = Thread.currentThread();
/** is this responder running? */
/** is this responder running? - synchronization using monitor lock */
private volatile boolean running = true;
/** input from the next downstream datanode */
private final DataInputStream downstreamIn;
/** output to upstream datanode/client */
private final DataOutputStream upstreamOut;
/** The type of this responder */
private final PacketResponderType type;
/** for log and error messages */
@ -812,8 +808,7 @@ public String toString() {
}
PacketResponder(final DataOutputStream upstreamOut,
final DataInputStream downstreamIn,
final DatanodeInfo[] downstreams) {
final DataInputStream downstreamIn, final DatanodeInfo[] downstreams) {
this.downstreamIn = downstreamIn;
this.upstreamOut = upstreamOut;
@ -830,31 +825,49 @@ public String toString() {
this.myString = b.toString();
}
private boolean isRunning() {
return running && datanode.shouldRun;
}
/**
* enqueue the seqno that is still be to acked by the downstream datanode.
* @param seqno
* @param lastPacketInBlock
* @param offsetInBlock
*/
synchronized void enqueue(final long seqno,
final boolean lastPacketInBlock, final long offsetInBlock) {
if (running) {
void enqueue(final long seqno, final boolean lastPacketInBlock,
final long offsetInBlock) {
final Packet p = new Packet(seqno, lastPacketInBlock, offsetInBlock,
System.nanoTime());
if(LOG.isDebugEnabled()) {
LOG.debug(myString + ": enqueue " + p);
}
synchronized(this) {
if (running) {
ackQueue.addLast(p);
notifyAll();
}
}
}
/** Wait for a packet with given {@code seqno} to be enqueued to ackQueue */
synchronized Packet waitForAckHead(long seqno) throws InterruptedException {
while (isRunning() && ackQueue.size() == 0) {
if (LOG.isDebugEnabled()) {
LOG.debug(myString + ": seqno=" + seqno +
" waiting for local datanode to finish write.");
}
wait();
}
return isRunning() ? ackQueue.getFirst() : null;
}
/**
* wait for all pending packets to be acked. Then shutdown thread.
*/
@Override
public synchronized void close() {
while (running && ackQueue.size() != 0 && datanode.shouldRun) {
while (isRunning() && ackQueue.size() != 0) {
try {
wait();
} catch (InterruptedException e) {
@ -877,8 +890,7 @@ public synchronized void close() {
public void run() {
boolean lastPacketInBlock = false;
final long startTime = ClientTraceLog.isInfoEnabled() ? System.nanoTime() : 0;
while (running && datanode.shouldRun && !lastPacketInBlock) {
while (isRunning() && !lastPacketInBlock) {
long totalAckTimeNanos = 0;
boolean isInterrupted = false;
try {
@ -888,8 +900,7 @@ public void run() {
long seqno = PipelineAck.UNKOWN_SEQNO;
long ackRecvNanoTime = 0;
try {
if (type != PacketResponderType.LAST_IN_PIPELINE
&& !mirrorError) {
if (type != PacketResponderType.LAST_IN_PIPELINE && !mirrorError) {
// read an ack from downstream datanode
ack.readFields(downstreamIn);
ackRecvNanoTime = System.nanoTime();
@ -900,35 +911,30 @@ public void run() {
}
if (seqno != PipelineAck.UNKOWN_SEQNO
|| type == PacketResponderType.LAST_IN_PIPELINE) {
synchronized (this) {
while (running && datanode.shouldRun && ackQueue.size() == 0) {
if (LOG.isDebugEnabled()) {
LOG.debug(myString + ": seqno=" + seqno +
" waiting for local datanode to finish write.");
}
wait();
}
if (!running || !datanode.shouldRun) {
pkt = waitForAckHead(seqno);
if (!isRunning()) {
break;
}
pkt = ackQueue.getFirst();
expected = pkt.seqno;
if (type == PacketResponderType.HAS_DOWNSTREAM_IN_PIPELINE
&& seqno != expected) {
throw new IOException(myString + "seqno: expected="
+ expected + ", received=" + seqno);
throw new IOException(myString + "seqno: expected=" + expected
+ ", received=" + seqno);
}
if (type == PacketResponderType.HAS_DOWNSTREAM_IN_PIPELINE) {
// The total ack time includes the ack times of downstream nodes.
// The total ack time includes the ack times of downstream
// nodes.
// The value is 0 if this responder doesn't have a downstream
// DN in the pipeline.
totalAckTimeNanos = ackRecvNanoTime - pkt.ackEnqueueNanoTime;
// Report the elapsed time from ack send to ack receive minus
// the downstream ack time.
long ackTimeNanos = totalAckTimeNanos - ack.getDownstreamAckTimeNanos();
long ackTimeNanos = totalAckTimeNanos
- ack.getDownstreamAckTimeNanos();
if (ackTimeNanos < 0) {
if (LOG.isDebugEnabled()) {
LOG.debug("Calculated invalid ack time: " + ackTimeNanos + "ns.");
LOG.debug("Calculated invalid ack time: " + ackTimeNanos
+ "ns.");
}
} else {
datanode.metrics.addPacketAckRoundTripTimeNanos(ackTimeNanos);
@ -936,7 +942,6 @@ public void run() {
}
lastPacketInBlock = pkt.lastPacketInBlock;
}
}
} catch (InterruptedException ine) {
isInterrupted = true;
} catch (IOException ioe) {
@ -952,71 +957,29 @@ public void run() {
}
if (Thread.interrupted() || isInterrupted) {
/* The receiver thread cancelled this thread.
* We could also check any other status updates from the
* receiver thread (e.g. if it is ok to write to replyOut).
* It is prudent to not send any more status back to the client
* because this datanode has a problem. The upstream datanode
* will detect that this datanode is bad, and rightly so.
/*
* The receiver thread cancelled this thread. We could also check
* any other status updates from the receiver thread (e.g. if it is
* ok to write to replyOut). It is prudent to not send any more
* status back to the client because this datanode has a problem.
* The upstream datanode will detect that this datanode is bad, and
* rightly so.
*/
LOG.info(myString + ": Thread is interrupted.");
running = false;
continue;
}
// If this is the last packet in block, then close block
// file and finalize the block before responding success
if (lastPacketInBlock) {
BlockReceiver.this.close();
final long endTime = ClientTraceLog.isInfoEnabled() ? System.nanoTime() : 0;
block.setNumBytes(replicaInfo.getNumBytes());
datanode.data.finalizeBlock(block);
datanode.closeBlock(block, DataNode.EMPTY_DEL_HINT);
if (ClientTraceLog.isInfoEnabled() && isClient) {
long offset = 0;
DatanodeRegistration dnR =
datanode.getDNRegistrationForBP(block.getBlockPoolId());
ClientTraceLog.info(String.format(DN_CLIENTTRACE_FORMAT,
inAddr, myAddr, block.getNumBytes(),
"HDFS_WRITE", clientname, offset,
dnR.getStorageID(), block, endTime-startTime));
} else {
LOG.info("Received " + block + " size "
+ block.getNumBytes() + " from " + inAddr);
}
// Finalize the block and close the block file
finalizeBlock(startTime);
}
// construct my ack message
Status[] replies = null;
if (mirrorError) { // ack read error
replies = new Status[2];
replies[0] = Status.SUCCESS;
replies[1] = Status.ERROR;
} else {
short ackLen = type == PacketResponderType.LAST_IN_PIPELINE? 0
: ack.getNumOfReplies();
replies = new Status[1+ackLen];
replies[0] = Status.SUCCESS;
for (int i=0; i<ackLen; i++) {
replies[i+1] = ack.getReply(i);
}
}
PipelineAck replyAck = new PipelineAck(expected, replies, totalAckTimeNanos);
if (replyAck.isSuccess() &&
pkt.offsetInBlock > replicaInfo.getBytesAcked())
replicaInfo.setBytesAcked(pkt.offsetInBlock);
// send my ack back to upstream datanode
replyAck.write(upstreamOut);
upstreamOut.flush();
if (LOG.isDebugEnabled()) {
LOG.debug(myString + ", replyAck=" + replyAck);
}
sendAckUpstream(ack, expected, totalAckTimeNanos,
(pkt != null ? pkt.offsetInBlock : 0));
if (pkt != null) {
// remove the packet from the ack queue
removeAckHead();
// update bytes acked
}
} catch (IOException e) {
LOG.warn("IOException in BlockReceiver.run(): ", e);
@ -1043,6 +1006,66 @@ public void run() {
LOG.info(myString + " terminating");
}
/**
* Finalize the block and close the block file
* @param startTime time when BlockReceiver started receiving the block
*/
private void finalizeBlock(long startTime) throws IOException {
BlockReceiver.this.close();
final long endTime = ClientTraceLog.isInfoEnabled() ? System.nanoTime()
: 0;
block.setNumBytes(replicaInfo.getNumBytes());
datanode.data.finalizeBlock(block);
datanode.closeBlock(block, DataNode.EMPTY_DEL_HINT);
if (ClientTraceLog.isInfoEnabled() && isClient) {
long offset = 0;
DatanodeRegistration dnR = datanode.getDNRegistrationForBP(block
.getBlockPoolId());
ClientTraceLog.info(String.format(DN_CLIENTTRACE_FORMAT, inAddr,
myAddr, block.getNumBytes(), "HDFS_WRITE", clientname, offset,
dnR.getStorageID(), block, endTime - startTime));
} else {
LOG.info("Received " + block + " size " + block.getNumBytes()
+ " from " + inAddr);
}
}
/**
* @param ack Ack received from downstream
* @param seqno sequence number of ack to be sent upstream
* @param totalAckTimeNanos total ack time including all the downstream
* nodes
* @param offsetInBlock offset in block for the data in packet
*/
private void sendAckUpstream(PipelineAck ack, long seqno,
long totalAckTimeNanos, long offsetInBlock) throws IOException {
Status[] replies = null;
if (mirrorError) { // ack read error
replies = MIRROR_ERROR_STATUS;
} else {
short ackLen = type == PacketResponderType.LAST_IN_PIPELINE ? 0 : ack
.getNumOfReplies();
replies = new Status[1 + ackLen];
replies[0] = Status.SUCCESS;
for (int i = 0; i < ackLen; i++) {
replies[i + 1] = ack.getReply(i);
}
}
PipelineAck replyAck = new PipelineAck(seqno, replies,
totalAckTimeNanos);
if (replyAck.isSuccess()
&& offsetInBlock > replicaInfo.getBytesAcked()) {
replicaInfo.setBytesAcked(offsetInBlock);
}
// send my ack back to upstream datanode
replyAck.write(upstreamOut);
upstreamOut.flush();
if (LOG.isDebugEnabled()) {
LOG.debug(myString + ", replyAck=" + replyAck);
}
}
/**
* Remove a packet from the head of the ack queue
*