Re: kafka stream - sliding window - getting unexpected output

Matthias J. Sax Wed, 18 May 2022 09:51:16 -0700

Emitting intermediate result is by-design.

If you don't want to get intermediate result, you can add `suppress()`after the aggregation and configure it to only "emit on window close".


-Matthias

On 5/17/22 3:20 AM, Shankar Mane wrote:

Hi All,

Our use case is to use sliding window. (for e.g. at any point, whenever

user performs any actions at time [ t1 ], we would like to see his activity
in [ t1 - last 24 hours]. Using this, to show the user some recommendations.




-- I have code ready and it works without any errors.
-- aggregations happen as expected.
-- but the output generated is unexpected. As windows gets slides, i am
getting mixed output which includes intermediate aggregated records also
coming with final aggregated outputs.

Could someone please help me here ?  what can I do here to get ONLY final
aggregated output.


Code snippet :
________________________________________________________________



builder.stream(tempReadingTopic, Consumed.with(stringSerde, inputSerde))
                 .filter((k, v) -> v != null)
                 .map((k,v) -> KeyValue.pair(v.getUserId(), v))
                 //.through("slidingbykey",
Produced.with(Serdes.String(), inputSerde))
                 .groupByKey()

.windowedBy(SlidingWindows.ofTimeDifferenceAndGrace(Duration.ofMillis(5000),
windowDuration))
                 .aggregate(OutputPojo::new, (k, tr, out) -> {
                     out.setUserId(tr.getUserId());
                     out.setCount(out.getCount() +1);
                     out.setSum(out.getSum() + tr.getInt4());
                     out.setUuid(tr.getUuid());

out.setStrTime(TimestampLongToString.getTime(tr.getTimestamp()));
                     waitForMs(200); //added delay just for analysing output
                     return out;
                 }, Materialized.with(stringSerde, outputSerde))
                 .suppress(Suppressed.untilTimeLimit(windowDuration,
Suppressed.BufferConfig.unbounded()))
                 .toStream()
                 .map((Windowed<String> key, OutputPojo out) -> {
                     return new KeyValue<>(key.key(),out) ;
                 })
                 .print(Printed.toSysOut());
//                .to(aveTempOutputTopic, Produced.with(stringSerde,
outputSerde))
                 ;



________________________________________________________________


Input data :

for i in {1..10}; do sleep 1s;python3 del.py 1001 10;sleep 1s; done

{'userId': '1001', 'timestamp': 1652781716234, 'int4': 10, 'uuid':
'64f019ee-9cf4-427d-b4c9-f2b5f88820e1'}
{'userId': '1001', 'timestamp': 1652781718436, 'int4': 10, 'uuid':
'cf173b3e-c34f-470a-ba15-ef648d0be8b9'}
{'userId': '1001', 'timestamp': 1652781720634, 'int4': 10, 'uuid':
'48d2b4ea-052d-42fa-a998-0216d928c034'}
{'userId': '1001', 'timestamp': 1652781722832, 'int4': 10, 'uuid':
'55a6c26c-3d2c-46f1-ab3c-04927f660cbe'}
{'userId': '1001', 'timestamp': 1652781725029, 'int4': 10, 'uuid':
'dbfd8cee-565d-496b-b5a8-773ae64bc518'}
{'userId': '1001', 'timestamp': 1652781727227, 'int4': 10, 'uuid':
'135dc5cd-50cb-467b-9e63-300fdeedaf75'}
{'userId': '1001', 'timestamp': 1652781729425, 'int4': 10, 'uuid':
'66d8e3c7-8f63-43ca-acf1-e39619bf33a0'}
{'userId': '1001', 'timestamp': 1652781731623, 'int4': 10, 'uuid':
'f037712b-42a5-4449-bcc2-cf6eafddf5ad'}
{'userId': '1001', 'timestamp': 1652781733820, 'int4': 10, 'uuid':
'7baa4254-b9da-43dc-bbb7-4caede578aeb'}
{'userId': '1001', 'timestamp': 1652781736018, 'int4': 10, 'uuid':
'16541989-f3ba-49f6-bd31-bf8a75ba8eac'}



________________________________________________________________


Output (*Unexpected*) :  below output is captured at each sliding window of
1s duration   (but input data is published at 2s of interval) :

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,

strTime=2022-05-17 15:31:28.263,
uuid=966277fd-3bdc-45c2-aa6a-c9c0dbe89c34)  ----> seems older UUID
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=1, sum=10.0,
strTime=2022-05-17 15:31:28.263, uuid=966277fd-3bdc-45c2-aa6a-c9c0dbe89c34)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=1, sum=10.0,
strTime=2022-05-17 15:31:56.234, uuid=64f019ee-9cf4-427d-b4c9-f2b5f88820e1)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:31:58.436, uuid=cf173b3e-c34f-470a-ba15-ef648d0be8b9)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:00.634, uuid=48d2b4ea-052d-42fa-a998-0216d928c034)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,
strTime=2022-05-17 15:32:00.634, uuid=48d2b4ea-052d-42fa-a998-0216d928c034)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:02.832, uuid=55a6c26c-3d2c-46f1-ab3c-04927f660cbe)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,
strTime=2022-05-17 15:32:02.832, uuid=55a6c26c-3d2c-46f1-ab3c-04927f660cbe)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:05.029, uuid=dbfd8cee-565d-496b-b5a8-773ae64bc518)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,
strTime=2022-05-17 15:32:05.029, uuid=dbfd8cee-565d-496b-b5a8-773ae64bc518)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:07.227, uuid=135dc5cd-50cb-467b-9e63-300fdeedaf75)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,
strTime=2022-05-17 15:32:07.227, uuid=135dc5cd-50cb-467b-9e63-300fdeedaf75)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:09.425, uuid=66d8e3c7-8f63-43ca-acf1-e39619bf33a0)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,
strTime=2022-05-17 15:32:09.425, uuid=66d8e3c7-8f63-43ca-acf1-e39619bf33a0)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:11.623, uuid=f037712b-42a5-4449-bcc2-cf6eafddf5ad)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,
strTime=2022-05-17 15:32:11.623, uuid=f037712b-42a5-4449-bcc2-cf6eafddf5ad)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:13.820, uuid=7baa4254-b9da-43dc-bbb7-4caede578aeb)

[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=3, sum=30.0,
strTime=2022-05-17 15:32:13.820, uuid=7baa4254-b9da-43dc-bbb7-4caede578aeb)
[KSTREAM-MAP-0000000011]: 1001, OutputPojo(userId=1001, count=2, sum=20.0,
strTime=2022-05-17 15:32:16.018, uuid=16541989-f3ba-49f6-bd31-bf8a75ba8eac)



Regards,
Shankar

Re: kafka stream - sliding window - getting unexpected output

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