scwhittle commented on code in PR #32456:
URL: https://github.com/apache/beam/pull/32456#discussion_r1768193743
##########
sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/ReadFromKafkaDoFn.java:
##########
@@ -511,6 +532,9 @@ public ProcessContinuation processElement(
}
}
}
+ LOG.warn(
+ "{} records were skipped because of seek returning an earlier
position.",
Review Comment:
how about
{} records were skipped due to seek returning to earlier position than
requested position of {}
##########
sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/ReadFromKafkaDoFn.java:
##########
@@ -460,7 +460,28 @@ public ProcessContinuation processElement(
}
return ProcessContinuation.resume();
}
+ long skippedRecords = 0L;
+ final Stopwatch sw = Stopwatch.createStarted();
for (ConsumerRecord<byte[], byte[]> rawRecord : rawRecords) {
+ // If the Kafka consumer returns a record with an offset that is
already processed
+ // the record can be safely skipped. This is needed because there is
a possibility
+ // that the seek() above fails to move the offset to the desired
position. In which
+ // case poll() would return records that are already cnsumed.
+ if (rawRecord.offset() < startOffset) {
+ // If the start offset is not reached even after skipping the
records for 10 seconds
+ // then the processing is stopped with a backoff to give the Kakfa
server some time
+ // catch up.
+ if (sw.elapsed().getSeconds() > 10L) {
+ LOG.error(
+ "The expected offset was not reached even after skipping
consumed records for 10 seconds,"
+ + " the processing of this bundle will be attempted at a
later time.");
+ return ProcessContinuation.resume()
+
.withResumeDelay(org.joda.time.Duration.standardSeconds(10L));
+ } else {
+ skippedRecords++;
+ continue;
+ }
+ }
if (!tracker.tryClaim(rawRecord.offset())) {
Review Comment:
I think you should have
if (skippedRecords > 0) {
LOG.warn(....) // about skipping
}
here instead.
Below you are going to log it separately for every batch of rawRecords and
you also will log it for skipping 0 records.
##########
sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/ReadFromKafkaDoFn.java:
##########
@@ -460,7 +460,28 @@ public ProcessContinuation processElement(
}
return ProcessContinuation.resume();
}
+ long skippedRecords = 0L;
+ final Stopwatch sw = Stopwatch.createStarted();
for (ConsumerRecord<byte[], byte[]> rawRecord : rawRecords) {
+ // If the Kafka consumer returns a record with an offset that is
already processed
+ // the record can be safely skipped. This is needed because there is
a possibility
+ // that the seek() above fails to move the offset to the desired
position. In which
+ // case poll() would return records that are already cnsumed.
+ if (rawRecord.offset() < startOffset) {
+ // If the start offset is not reached even after skipping the
records for 10 seconds
+ // then the processing is stopped with a backoff to give the Kakfa
server some time
+ // catch up.
+ if (sw.elapsed().getSeconds() > 10L) {
+ LOG.error(
+ "The expected offset was not reached even after skipping
consumed records for 10 seconds,"
Review Comment:
would be good to include the offset reached and what the startOffset is to
help with debugging
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