### What changes were proposed in this pull request?
Please refer https://issues.apache.org/jira/browse/SPARK-24634 to see rationalization of the issue.
This patch adds a new metric to count the number of inputs arrived later than watermark plus allowed delay. To make changes simpler, this patch doesn't count the exact number of input rows which are later than watermark plus allowed delay. Instead, this patch counts the inputs which are dropped in the logic of operator. The difference of twos are shown in streaming aggregation: to optimize the calculation, streaming aggregation "pre-aggregates" the input rows, and later checks the lateness against "pre-aggregated" inputs, hence the number might be reduced.
The new metric will be provided via two places:
1. On Spark UI: check the metrics in stateful operator nodes in query execution details page in SQL tab
2. On Streaming Query Listener: check "numLateInputs" in "stateOperators" in QueryProcessEvent.
### Why are the changes needed?
Dropping late inputs means that end users might not get expected outputs. Even end users may indicate the fact and tolerate the result (as that's what allowed lateness is for), but they should be able to observe whether the current value of allowed lateness drops inputs or not so that they can adjust the value.
Also, whatever the chance they have multiple of stateful operators in a single query, if Spark drops late inputs "between" these operators, it becomes "correctness" issue. Spark should disallow such possibility, but given we already provided the flexibility, at least we should provide the way to observe the correctness issue and decide whether they should make correction of their query or not.
### Does this PR introduce _any_ user-facing change?
Yes. End users will be able to retrieve the information of late inputs via two ways:
1. SQL tab in Spark UI
2. Streaming Query Listener
### How was this patch tested?
New UTs added & existing UTs are modified to reflect the change.
And ran manual test reproducing SPARK-28094.
I've picked the specific case on "B outer C outer D" which is enough to represent the "intermediate late row" issue due to global watermark.
https://gist.github.com/jammann/b58bfbe0f4374b89ecea63c1e32c8f17
Spark logs warning message on the query which means SPARK-28074 is working correctly,
```
20/05/30 17:52:47 WARN UnsupportedOperationChecker: Detected pattern of possible 'correctness' issue due to global watermark. The query contains stateful operation which can emit rows older than the current watermark plus allowed late record delay, which are "late rows" in downstream stateful operations and these rows can be discarded. Please refer the programming guide doc for more details.;
Join LeftOuter, ((D_FK#28 = D_ID#87) AND (B_LAST_MOD#26-T30000ms = D_LAST_MOD#88-T30000ms))
:- Join LeftOuter, ((C_FK#27 = C_ID#58) AND (B_LAST_MOD#26-T30000ms = C_LAST_MOD#59-T30000ms))
: :- EventTimeWatermark B_LAST_MOD#26: timestamp, 30 seconds
: : +- Project [v#23.B_ID AS B_ID#25, v#23.B_LAST_MOD AS B_LAST_MOD#26, v#23.C_FK AS C_FK#27, v#23.D_FK AS D_FK#28]
: : +- Project [from_json(StructField(B_ID,StringType,false), StructField(B_LAST_MOD,TimestampType,false), StructField(C_FK,StringType,true), StructField(D_FK,StringType,true), value#21, Some(UTC)) AS v#23]
: : +- Project [cast(value#8 as string) AS value#21]
: : +- StreamingRelationV2 org.apache.spark.sql.kafka010.KafkaSourceProvider3a7fd18c, kafka, org.apache.spark.sql.kafka010.KafkaSourceProvider$KafkaTable396d2958, org.apache.spark.sql.util.CaseInsensitiveStringMapa51ee61a, [key#7, value#8, topic#9, partition#10, offset#11L, timestamp#12, timestampType#13], StreamingRelation DataSource(org.apache.spark.sql.SparkSessiond221af8,kafka,List(),None,List(),None,Map(inferSchema -> true, startingOffsets -> earliest, subscribe -> B, kafka.bootstrap.servers -> localhost:9092),None), kafka, [key#0, value#1, topic#2, partition#3, offset#4L, timestamp#5, timestampType#6]
: +- EventTimeWatermark C_LAST_MOD#59: timestamp, 30 seconds
: +- Project [v#56.C_ID AS C_ID#58, v#56.C_LAST_MOD AS C_LAST_MOD#59]
: +- Project [from_json(StructField(C_ID,StringType,false), StructField(C_LAST_MOD,TimestampType,false), value#54, Some(UTC)) AS v#56]
: +- Project [cast(value#41 as string) AS value#54]
: +- StreamingRelationV2 org.apache.spark.sql.kafka010.KafkaSourceProvider3f507373, kafka, org.apache.spark.sql.kafka010.KafkaSourceProvider$KafkaTable7b6736a4, org.apache.spark.sql.util.CaseInsensitiveStringMapa51ee61b, [key#40, value#41, topic#42, partition#43, offset#44L, timestamp#45, timestampType#46], StreamingRelation DataSource(org.apache.spark.sql.SparkSessiond221af8,kafka,List(),None,List(),None,Map(inferSchema -> true, startingOffsets -> earliest, subscribe -> C, kafka.bootstrap.servers -> localhost:9092),None), kafka, [key#33, value#34, topic#35, partition#36, offset#37L, timestamp#38, timestampType#39]
+- EventTimeWatermark D_LAST_MOD#88: timestamp, 30 seconds
+- Project [v#85.D_ID AS D_ID#87, v#85.D_LAST_MOD AS D_LAST_MOD#88]
+- Project [from_json(StructField(D_ID,StringType,false), StructField(D_LAST_MOD,TimestampType,false), value#83, Some(UTC)) AS v#85]
+- Project [cast(value#70 as string) AS value#83]
+- StreamingRelationV2 org.apache.spark.sql.kafka010.KafkaSourceProvider2b90e779, kafka, org.apache.spark.sql.kafka010.KafkaSourceProvider$KafkaTable36f8cd29, org.apache.spark.sql.util.CaseInsensitiveStringMapa51ee620, [key#69, value#70, topic#71, partition#72, offset#73L, timestamp#74, timestampType#75], StreamingRelation DataSource(org.apache.spark.sql.SparkSessiond221af8,kafka,List(),None,List(),None,Map(inferSchema -> true, startingOffsets -> earliest, subscribe -> D, kafka.bootstrap.servers -> localhost:9092),None), kafka, [key#62, value#63, topic#64, partition#65, offset#66L, timestamp#67, timestampType#68]
```
and we can find the late inputs from the batch 4 as follows:
which represents intermediate inputs are being lost, ended up with correctness issue.
Closes#28607 from HeartSaVioR/SPARK-24634-v3.
Authored-by: Jungtaek Lim (HeartSaVioR) <kabhwan.opensource@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
84815d0550
