nehsyc commented on a change in pull request #12726:
URL: https://github.com/apache/beam/pull/12726#discussion_r487443128
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/GroupIntoBatches.java
##########
@@ -150,70 +185,96 @@ public long apply(long left, long right) {
});
this.keySpec = StateSpecs.value(inputKeyCoder);
- // prefetch every 20% of batchSize elements. Do not prefetch if
batchSize is too little
+ // Prefetch every 20% of batchSize elements. Do not prefetch if
batchSize is too little
this.prefetchFrequency = ((batchSize / 5) <= 1) ? Long.MAX_VALUE :
(batchSize / 5);
}
@ProcessElement
public void processElement(
- @TimerId(END_OF_WINDOW_ID) Timer timer,
+ @TimerId(END_OF_WINDOW_ID) Timer windowTimer,
+ @TimerId(END_OF_BUFFERING_ID) Timer bufferingTimer,
@StateId(BATCH_ID) BagState<InputT> batch,
@StateId(NUM_ELEMENTS_IN_BATCH_ID) CombiningState<Long, long[], Long>
numElementsInBatch,
@StateId(KEY_ID) ValueState<K> key,
@Element KV<K, InputT> element,
BoundedWindow window,
OutputReceiver<KV<K, Iterable<InputT>>> receiver) {
- Instant windowExpires = window.maxTimestamp().plus(allowedLateness);
-
- LOG.debug(
- "*** SET TIMER *** to point in time {} for window {}",
- windowExpires.toString(),
- window.toString());
- timer.set(windowExpires);
+ Instant windowEnds = window.maxTimestamp().plus(allowedLateness);
+ LOG.debug("*** SET TIMER *** to point in time {} for window {}",
windowEnds, window);
+ windowTimer.set(windowEnds);
key.write(element.getKey());
+ LOG.debug("*** BATCH *** Add element for window {} ", window);
batch.add(element.getValue());
- LOG.debug("*** BATCH *** Add element for window {} ", window.toString());
- // blind add is supported with combiningState
+ // Blind add is supported with combiningState
numElementsInBatch.add(1L);
+
Long num = numElementsInBatch.read();
+ if (num == 1 && maxBufferingDuration.isLongerThan(Duration.ZERO)) {
+ // This is the first element in batch. Start counting buffering time
if a limit was set.
+ bufferingTimer.offset(maxBufferingDuration).setRelative();
+ }
if (num % prefetchFrequency == 0) {
- // prefetch data and modify batch state (readLater() modifies this)
+ // Prefetch data and modify batch state (readLater() modifies this)
batch.readLater();
}
if (num >= batchSize) {
LOG.debug("*** END OF BATCH *** for window {}", window.toString());
- flushBatch(receiver, key, batch, numElementsInBatch);
+ flushBatch(receiver, key, batch, numElementsInBatch, bufferingTimer);
}
}
+ @OnTimer(END_OF_BUFFERING_ID)
+ public void onBufferingTimer(
+ OutputReceiver<KV<K, Iterable<InputT>>> receiver,
+ @Timestamp Instant timestamp,
+ @StateId(KEY_ID) ValueState<K> key,
+ @StateId(BATCH_ID) BagState<InputT> batch,
+ @StateId(NUM_ELEMENTS_IN_BATCH_ID) CombiningState<Long, long[], Long>
numElementsInBatch,
+ @TimerId(END_OF_BUFFERING_ID) Timer bufferingTimer) {
+ LOG.debug(
+ "*** END OF BUFFERING *** for timer timestamp {} with buffering
duration {}",
+ timestamp,
+ maxBufferingDuration);
+ flushBatch(receiver, key, batch, numElementsInBatch, bufferingTimer);
Review comment:
Good catch! Corrected.
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/GroupIntoBatches.java
##########
@@ -66,25 +68,49 @@
* }
* }}));
* </pre>
+ *
+ * <p>Example 2 (batch unbounded input in a global window):
+ *
+ * <pre>{@code
+ * PCollection<KV<String, String>> unboundedInput = ...;
+ * long batchSize = 100L;
+ * Duration maxBufferingDuration = Duration.standardSeconds(10);
+ * PCollection<KV<String, Iterable<String>>> batched = unboundedInput
+ * .apply(Window.<KV<String, String>>into(new GlobalWindows())
+ * .triggering(Repeatedly.forever(AfterPane.elementCountAtLeast(1)))
+ * .discardingFiredPanes())
+ * .apply(GroupIntoBatches.<String, String>ofSize(batchSize)
+ * .withMaxBufferingDuration(maxBufferingDuration));
+ * }</pre>
*/
public class GroupIntoBatches<K, InputT>
extends PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K,
Iterable<InputT>>>> {
private final long batchSize;
+ private final Duration maxBufferingDuration;
- private GroupIntoBatches(long batchSize) {
+ private GroupIntoBatches(long batchSize, Duration maxBufferingDuration) {
this.batchSize = batchSize;
+ this.maxBufferingDuration = maxBufferingDuration;
}
public static <K, InputT> GroupIntoBatches<K, InputT> ofSize(long batchSize)
{
- return new GroupIntoBatches<>(batchSize);
+ return new GroupIntoBatches<>(batchSize, Duration.ZERO);
}
/** Returns the size of the batch. */
public long getBatchSize() {
return batchSize;
}
+ /**
+ * Set a time limit (in processing time) on how long an incomplete batch of
elements is allowed to
+ * be buffered. Once a batch is flushed to output, the timer is reset.
+ */
+ public GroupIntoBatches<K, InputT> withMaxBufferingDuration(Duration
duration) {
+ return new GroupIntoBatches<>(batchSize, duration);
Review comment:
Added a check. But we still need additional checks on null value. See my
reply below.
##########
File path:
sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/GroupIntoBatches.java
##########
@@ -66,25 +68,49 @@
* }
* }}));
* </pre>
+ *
+ * <p>Example 2 (batch unbounded input in a global window):
+ *
+ * <pre>{@code
+ * PCollection<KV<String, String>> unboundedInput = ...;
+ * long batchSize = 100L;
+ * Duration maxBufferingDuration = Duration.standardSeconds(10);
+ * PCollection<KV<String, Iterable<String>>> batched = unboundedInput
+ * .apply(Window.<KV<String, String>>into(new GlobalWindows())
+ * .triggering(Repeatedly.forever(AfterPane.elementCountAtLeast(1)))
+ * .discardingFiredPanes())
+ * .apply(GroupIntoBatches.<String, String>ofSize(batchSize)
+ * .withMaxBufferingDuration(maxBufferingDuration));
+ * }</pre>
*/
public class GroupIntoBatches<K, InputT>
extends PTransform<PCollection<KV<K, InputT>>, PCollection<KV<K,
Iterable<InputT>>>> {
private final long batchSize;
+ private final Duration maxBufferingDuration;
- private GroupIntoBatches(long batchSize) {
+ private GroupIntoBatches(long batchSize, Duration maxBufferingDuration) {
this.batchSize = batchSize;
+ this.maxBufferingDuration = maxBufferingDuration;
}
public static <K, InputT> GroupIntoBatches<K, InputT> ofSize(long batchSize)
{
- return new GroupIntoBatches<>(batchSize);
+ return new GroupIntoBatches<>(batchSize, Duration.ZERO);
Review comment:
Changed it to null.
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