apurtell commented on a change in pull request #2987:
URL: https://github.com/apache/hbase/pull/2987#discussion_r583087218
##########
File path:
hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplicationSourceWALReader.java
##########
@@ -245,22 +270,37 @@ private void handleEmptyWALEntryBatch() throws
InterruptedException {
}
/**
- * if we get an EOF due to a zero-length log, and there are other logs in
queue
- * (highly likely we've closed the current log), and autorecovery is
- * enabled, then dump the log
+ * This is to handle the EOFException from the WAL entry stream.
EOFException should
+ * be handled carefully because there are chances of data loss because of
never replicating
+ * the data. Thus we should always try to ship existing batch of entries
here.
+ * If there was only one log in the queue before EOF, we ship the empty
batch here
+ * and since reader is still active, in the next iteration of reader we will
+ * stop the reader.
+ * If there was more than one log in the queue before EOF, we ship the
existing batch
+ * and reset the wal patch and position to the log with EOF, so shipper can
remove
+ * logs from replication queue
* @return true only the IOE can be handled
*/
- private boolean handleEofException(IOException e) {
+ private boolean handleEofException(IOException e, WALEntryBatch batch)
+ throws InterruptedException {
PriorityBlockingQueue<Path> queue = logQueue.getQueue(walGroupId);
// Dump the log even if logQueue size is 1 if the source is from recovered
Source
// since we don't add current log to recovered source queue so it is safe
to remove.
- if ((e instanceof EOFException || e.getCause() instanceof EOFException) &&
- (source.isRecovered() || queue.size() > 1) && this.eofAutoRecovery) {
+ if ((e instanceof EOFException || e.getCause() instanceof EOFException)
+ && (source.isRecovered() || queue.size() > 1)
+ && this.eofAutoRecovery) {
try {
if (fs.getFileStatus(queue.peek()).getLen() == 0) {
Review comment:
There is a potential race here. queue.peek() is called twice, and can
return different results. (There's no guarantee that it won't, right?) A local
variable should be assigned just before this line and reused, e.g.
Path head = queue.peek();
if (fs.getFileStatus(head.getLen() == 0) {
LOG.warn("Forcing removal of 0 length log in queue: {}", head);
...
batch.setLastWalPath(head);
...
}
##########
File path:
hbase-server/src/main/java/org/apache/hadoop/hbase/replication/regionserver/ReplicationSourceWALReader.java
##########
@@ -123,44 +122,64 @@ public ReplicationSourceWALReader(FileSystem fs,
Configuration conf,
@Override
public void run() {
int sleepMultiplier = 1;
- while (isReaderRunning()) { // we only loop back here if something fatal
happened to our stream
- try (WALEntryStream entryStream =
- new WALEntryStream(logQueue, conf, currentPosition,
- source.getWALFileLengthProvider(),
source.getServerWALsBelongTo(),
- source.getSourceMetrics(), walGroupId)) {
- while (isReaderRunning()) { // loop here to keep reusing stream while
we can
- if (!source.isPeerEnabled()) {
- Threads.sleep(sleepForRetries);
- continue;
- }
- if (!checkQuota()) {
- continue;
+ WALEntryBatch batch = null;
+ WALEntryStream entryStream = null;
+ try {
+ // we only loop back here if something fatal happened to our stream
+ while (isReaderRunning()) {
+ try {
+ entryStream =
+ new WALEntryStream(logQueue, conf, currentPosition,
source.getWALFileLengthProvider(),
+ source.getServerWALsBelongTo(), source.getSourceMetrics(),
walGroupId);
+ while (isReaderRunning()) { // loop here to keep reusing stream
while we can
+ if (!source.isPeerEnabled()) {
+ Threads.sleep(sleepForRetries);
+ continue;
+ }
+ if (!checkQuota()) {
+ continue;
+ }
+
+ batch = createBatch(entryStream);
+ batch = readWALEntries(entryStream, batch);
+ currentPosition = entryStream.getPosition();
+ if (batch == null) {
+ // either the queue have no WAL to read
+ // or got no new entries (didn't advance position in WAL)
+ handleEmptyWALEntryBatch();
+ entryStream.reset(); // reuse stream
+ } else {
+ addBatchToShippingQueue(batch);
+ }
}
- WALEntryBatch batch = readWALEntries(entryStream);
- currentPosition = entryStream.getPosition();
- if (batch != null) {
- // need to propagate the batch even it has no entries since it may
carry the last
- // sequence id information for serial replication.
- LOG.debug("Read {} WAL entries eligible for replication",
batch.getNbEntries());
- entryBatchQueue.put(batch);
+ } catch (IOException e) { // stream related
+ if (handleEofException(e, batch)) {
sleepMultiplier = 1;
- } else { // got no entries and didn't advance position in WAL
- handleEmptyWALEntryBatch();
- entryStream.reset(); // reuse stream
+ } else {
+ LOG.warn("Failed to read stream of replication entries", e);
+ if (sleepMultiplier < maxRetriesMultiplier) {
+ sleepMultiplier++;
+ }
+ Threads.sleep(sleepForRetries * sleepMultiplier);
}
+ } catch (InterruptedException e) {
+ LOG.trace("Interrupted while sleeping between WAL reads");
+ Thread.currentThread().interrupt();
+ } finally {
+ entryStream.close();
Review comment:
See earlier branch-1 review as to why the try blocks have been
restructured here. lgtm
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