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Posted to issues@beam.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2021/11/03 23:00:03 UTC
[jira] [Work logged] (BEAM-12999) Improve Reshuffle Transform
[ https://issues.apache.org/jira/browse/BEAM-12999?focusedWorklogId=675018&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-675018 ]
ASF GitHub Bot logged work on BEAM-12999:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 03/Nov/21 22:59
Start Date: 03/Nov/21 22:59
Worklog Time Spent: 10m
Work Description: robertwb commented on a change in pull request #15665:
URL: https://github.com/apache/beam/pull/15665#discussion_r742406333
##########
File path: sdks/java/core/src/main/java/org/apache/beam/sdk/transforms/Reshuffle.java
##########
@@ -36,102 +36,121 @@
/**
* <b>For internal use only; no backwards compatibility guarantees.</b>
*
- * <p>A {@link PTransform} that returns a {@link PCollection} equivalent to its input but
+ * <p>{@link PTransform}(s) that returns a {@link PCollection} equivalent to its input but
* operationally provides some of the side effects of a {@link GroupByKey}, in particular
* checkpointing, and preventing fusion of the surrounding transforms.
*
* <p>Performs a {@link GroupByKey} so that the data is key-partitioned. Configures the {@link
* WindowingStrategy} so that no data is dropped, but doesn't affect the need for the user to
* specify allowed lateness and accumulation mode before a user-inserted GroupByKey.
- *
- * @param <K> The type of key being reshuffled on.
- * @param <V> The type of value being reshuffled.
- * @deprecated this transform's intended side effects are not portable; it will likely be removed
*/
@Internal
-@Deprecated
-public class Reshuffle<K, V> extends PTransform<PCollection<KV<K, V>>, PCollection<KV<K, V>>> {
+public class Reshuffle {
private Reshuffle() {}
- public static <K, V> Reshuffle<K, V> of() {
- return new Reshuffle<>();
+ /** @deprecated use {@link #perKey()}. */
+ @Deprecated
+ public static <K, V> PerKey<K, V> of() {
+ return new PerKey<>();
+ }
+
+ public static <K, V> PerKey<K, V> perKey() {
+ return new PerKey<>();
+ }
+
+ /** @deprecated use {@link #perRandomKey()}. */
+ @Deprecated
+ public static <T> PerRandomKey<T> viaRandomKey() {
+ return perRandomKey();
}
/**
- * Encapsulates the sequence "pair input with unique key, apply {@link Reshuffle#of}, drop the
- * key" commonly used to break fusion.
+ * Encapsulates the sequence "pair input with unique key, apply {@link Reshuffle#perKey()}, drop
+ * the key" commonly used to break fusion.
*/
@Experimental
- public static <T> ViaRandomKey<T> viaRandomKey() {
- return new ViaRandomKey<>();
- }
-
- @Override
- public PCollection<KV<K, V>> expand(PCollection<KV<K, V>> input) {
- WindowingStrategy<?, ?> originalStrategy = input.getWindowingStrategy();
- // If the input has already had its windows merged, then the GBK that performed the merge
- // will have set originalStrategy.getWindowFn() to InvalidWindows, causing the GBK contained
- // here to fail. Instead, we install a valid WindowFn that leaves all windows unchanged.
- // The TimestampCombiner is set to ensure the GroupByKey does not shift elements forwards in
- // time.
- // Because this outputs as fast as possible, this should not hold the watermark.
- Window<KV<K, V>> rewindow =
- Window.<KV<K, V>>into(new IdentityWindowFn<>(originalStrategy.getWindowFn().windowCoder()))
- .triggering(new ReshuffleTrigger<>())
- .discardingFiredPanes()
- .withTimestampCombiner(TimestampCombiner.EARLIEST)
- .withAllowedLateness(Duration.millis(BoundedWindow.TIMESTAMP_MAX_VALUE.getMillis()));
-
- return input
- .apply(rewindow)
- .apply("ReifyOriginalTimestamps", Reify.timestampsInValue())
- .apply(GroupByKey.create())
- // Set the windowing strategy directly, so that it doesn't get counted as the user having
- // set allowed lateness.
- .setWindowingStrategyInternal(originalStrategy)
- .apply(
- "ExpandIterable",
- ParDo.of(
- new DoFn<KV<K, Iterable<TimestampedValue<V>>>, KV<K, TimestampedValue<V>>>() {
- @ProcessElement
- public void processElement(
- @Element KV<K, Iterable<TimestampedValue<V>>> element,
- OutputReceiver<KV<K, TimestampedValue<V>>> r) {
- K key = element.getKey();
- for (TimestampedValue<V> value : element.getValue()) {
- r.output(KV.of(key, value));
- }
- }
- }))
- .apply("RestoreOriginalTimestamps", ReifyTimestamps.extractFromValues());
+ public static <T> PerRandomKey<T> perRandomKey() {
+ return new PerRandomKey<>();
}
/** Implementation of {@link #viaRandomKey()}. */
- public static class ViaRandomKey<T> extends PTransform<PCollection<T>, PCollection<T>> {
- private ViaRandomKey() {}
+ public static class PerRandomKey<T> extends PTransform<PCollection<T>, PCollection<T>> {
+ private PerRandomKey() {}
- private ViaRandomKey(@Nullable Integer numBuckets) {
+ private PerRandomKey(@Nullable Integer numBuckets) {
this.numBuckets = numBuckets;
}
// The number of buckets to shard into. This is a performance optimization to prevent having
// unit sized bundles on the output. If unset, uses a random integer key.
private @Nullable Integer numBuckets;
- public ViaRandomKey<T> withNumBuckets(@Nullable Integer numBuckets) {
- return new ViaRandomKey<>(numBuckets);
+ public PerRandomKey<T> withNumBuckets(@Nullable Integer numBuckets) {
+ return new PerRandomKey<>(numBuckets);
}
@Override
public PCollection<T> expand(PCollection<T> input) {
return input
.apply("Pair with random key", ParDo.of(new AssignShardFn<>(numBuckets)))
- .apply(Reshuffle.of())
+ .apply(Reshuffle.perKey())
.apply(Values.create());
}
}
+ /**
+ * Implementation of {@link #perKey*()}.
+ *
+ * @param <K> The type of key being reshuffled on.
+ * @param <V> The type of value being reshuffled.
+ */
+ public static class PerKey<K, V>
Review comment:
No, we don't need to change this anymore, but we may need to implement `getKindString` for PerRandomKey which was renamed.
##########
File path: model/pipeline/src/main/proto/beam_runner_api.proto
##########
@@ -365,6 +365,12 @@ message StandardPTransforms {
// Represents the GroupIntoBatches.WithShardedKey operation.
// Payload: GroupIntoBatchesPayload
GROUP_INTO_BATCHES_WITH_SHARDED_KEY = 6 [(beam_urn) = "beam:transform:group_into_batches_with_sharded_key:v1"];
+
+ // Represents the Reshuffle.perKey() operation.
+ RESHUFFLE_PER_KEY = 7 [(beam_urn) = "beam:transform:reshuffle_per_key:v1"];
+
+ // Represents the Reshuffle.perRandomKey() operation.
+ RESHUFFLE_PER_RANDOM_KEY = 8 [(beam_urn) = "beam:transform:reshuffle_per_random_key:v1"];
Review comment:
Yes. We could rename `Reshuffle.perRandomKey()` to `Reshuffle.elements()` as well.
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Issue Time Tracking
-------------------
Worklog Id: (was: 675018)
Time Spent: 14h 50m (was: 14h 40m)
> Improve Reshuffle Transform
> ---------------------------
>
> Key: BEAM-12999
> URL: https://issues.apache.org/jira/browse/BEAM-12999
> Project: Beam
> Issue Type: Improvement
> Components: sdk-go, sdk-java-core, sdk-py-core
> Reporter: Ke Wu
> Assignee: Ke Wu
> Priority: P2
> Time Spent: 14h 50m
> Remaining Estimate: 0h
>
> See discussion [https://lists.apache.org/thread.html/r83adaad3a512ad186f2f9dc9dc4bec2a789070677c07cdcaad6fcfa5%40%3Cdev.beam.apache.org%3E]
>
> “beam:transform:reshuffle:v1" Transform represents different semantic transforms in different SDKs. The proposal is to replace "beam:transform:reshuffle:v1" with two new urns, one to represent reshuffle KV PCollection using the K, and the other to reshuffle based on random key.
>
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