I'm not sure if I fully understand this but let me check:
- if you start 2 instances, one instance will process half of the partitions,
the other instance will process the other half
- for any given key, like key 100, it will only be processed on one of the
instances, not both.
Does this help?
Eno
> On 15 Jun 2017, at 07:40, Sameer Kumar <sam.kum.w...@gmail.com> wrote:
>
> Also, I am writing a single key in the output all the time. I believe
> machine2 will have to write a key and since a state store is local it
> wouldn't know about the counter state on another machine. So, I guess this
> will happen.
>
> -Sameer.
>
> On Thu, Jun 15, 2017 at 11:11 AM, Sameer Kumar <sam.kum.w...@gmail.com>
> wrote:
>
>> The input topic contains 60 partitions and data is distributed well across
>> different partitions on different keys. While consumption, I am doing some
>> filtering and writing only single key data.
>>
>> Output would be something of the form:- Machine 1
>>
>> 2017-06-13 16:49:10 INFO LICountClickImprMR2:116 - licount
>> k=P:LIS:1236667:2017_06_13:I,v=651
>> 2017-06-13 16:49:30 INFO LICountClickImprMR2:116 - licount
>> k=P:LIS:1236667:2017_06_13:I,v=652
>>
>> Machine 2
>> 2017-06-13 16:49:10 INFO LICountClickImprMR2:116 - licount
>> k=P:LIS:1236667:2017_06_13:I,v=1
>> 2017-06-13 16:49:30 INFO LICountClickImprMR2:116 - licount
>> k=P:LIS:1236667:2017_06_13:I,v=2
>>
>> I am sharing a snippet of code,
>>
>> private KTable<String, Integer> extractLICount(KStream<Windowed<String>,
>> AdLog> joinedImprLogs) {
>> KTable<String, Integer> liCount = joinedImprLogs.flatMap((key, value)
>> -> {
>> List<KeyValue<String, Integer>> l = new ArrayList<>();
>> if (value == null) {
>> return l;
>> }
>> String date = new SimpleDateFormat("yyyy_MM_dd").format(new
>> Date(key.window().end()));
>> // Lineitemids
>> if (value != null && value.getAdLogType() == 3) {
>> // log.info("Invalid data: " + value);
>> return l;
>> }
>> if (value.getAdLogType() == 2) {
>> long lineitemid = value.getAdClickLog().getItmClmbLId();
>> if (lineitemid == TARGETED_LI) {
>> String liKey = String.format("P:LIS:%s:%s:C", lineitemid, date);
>> l.add(new KeyValue<>(liKey, 1));
>> }
>> return l;
>> } else if (value.getAdLogType() == 1){
>>
>> long[] lineitemids = value.getAdImprLog().getItmClmbLIds();
>> if (value.getAdImprLog().isVisible()) {
>> for (int i = 0; i < lineitemids.length; i++) {
>> long li = lineitemids[i];
>> if (li == TARGETED_LI) {
>> // log.info("valid impression ids= " +
>> value.getAdImprLog().toString());
>> String liKey = String.format("P:LIS:%s:%s:I", li, date);
>> l.add(new KeyValue<>(liKey, 1));
>> }
>> }
>> }
>> return l;
>> }
>> return l;
>> }).groupBy((k, v) -> k, Serdes.String(), Serdes.Integer())
>> .reduce((value1, value2) -> value1 + value2,
>> LINE_ITEM_COUNT_STORE);
>> return liCount;
>> }
>>
>> On Wed, Jun 14, 2017 at 10:55 AM, Sameer Kumar <sam.kum.w...@gmail.com>
>> wrote:
>>
>>> The input topic contains 60 partitions and data is distributed well
>>> across different partitions on different keys. While consumption, I am
>>> doing some filtering and writing only single key data.
>>>
>>> Output would be something of the form:- Machine 1
>>>
>>> 2017-06-13 16:49:10 INFO LICountClickImprMR2:116 - licount
>>> k=P:LIS:1236667:2017_06_13:I,v=651
>>> 2017-06-13 16:49:30 INFO LICountClickImprMR2:116 - licount
>>> k=P:LIS:1236667:2017_06_13:I,v=652
>>>
>>> Machine 2
>>> 2017-06-13 16:49:10 INFO LICountClickImprMR2:116 - licount
>>> k=P:LIS:1236667:2017_06_13:I,v=1
>>> 2017-06-13 16:49:30 INFO LICountClickImprMR2:116 - licount
>>> k=P:LIS:1236667:2017_06_13:I,v=2
>>>
>>> I am sharing a snippet of code,
>>>
>>> private KTable<String, Integer> extractLICount(KStream<Windowed<String>,
>>> AdLog> joinedImprLogs) {
>>> KTable<String, Integer> liCount = joinedImprLogs.flatMap((key, value)
>>> -> {
>>> List<KeyValue<String, Integer>> l = new ArrayList<>();
>>> if (value == null) {
>>> return l;
>>> }
>>> String date = new SimpleDateFormat("yyyy_MM_dd").format(new
>>> Date(key.window().end()));
>>> // Lineitemids
>>> if (value != null && value.getAdLogType() == 3) {
>>> // log.info("Invalid data: " + value);
>>> return l;
>>> }
>>> if (value.getAdLogType() == 2) {
>>> long lineitemid = value.getAdClickLog().getItmClmbLId();
>>> if (lineitemid == TARGETED_LI) {
>>> String liKey = String.format("P:LIS:%s:%s:C", lineitemid, date);
>>> l.add(new KeyValue<>(liKey, 1));
>>> }
>>> return l;
>>> } else if (value.getAdLogType() == 1){
>>>
>>> long[] lineitemids = value.getAdImprLog().getItmClmbLIds();
>>> if (value.getAdImprLog().isVisible()) {
>>> for (int i = 0; i < lineitemids.length; i++) {
>>> long li = lineitemids[i];
>>> if (li == TARGETED_LI) {
>>> // log.info("valid impression ids= " +
>>> value.getAdImprLog().toString());
>>> String liKey = String.format("P:LIS:%s:%s:I", li, date);
>>> l.add(new KeyValue<>(liKey, 1));
>>> }
>>> }
>>> }
>>> return l;
>>> }
>>> return l;
>>> }).groupBy((k, v) -> k, Serdes.String(), Serdes.Integer())
>>> .reduce((value1, value2) -> value1 + value2,
>>> LINE_ITEM_COUNT_STORE);
>>> return liCount;
>>> }
>>>
>>> -Sameer.
>>>
>>> On Tue, Jun 13, 2017 at 10:35 PM, Matthias J. Sax <matth...@confluent.io>
>>> wrote:
>>>
>>>> Sameer,
>>>>
>>>> if you write a single key, all your input data should be in a single
>>>> partition. As Streams scales out via partitions, you cannot have a
>>>> second instance as data from one partition is never split. Thus, all
>>>> data will go to one instance while the second instance should be idle.
>>>>
>>>> So what I don't understand is, why you see that machine 2 output a
>>>> counter of 1 -- it should not output anything. Maybe you can give some
>>>> more details about your setup?
>>>>
>>>> -Matthias
>>>>
>>>> On 6/13/17 5:00 AM, Sameer Kumar wrote:
>>>>> Hi,
>>>>>
>>>>> I witnessed a strange behaviour in KafkaStreams, need help in
>>>> understanding
>>>>> the same.
>>>>>
>>>>> I created an application for aggregating clicks per user, I want to
>>>> process
>>>>> it only for 1 user( i was writing only a single key).
>>>>> When I ran application on one machine, it was running fine.Now, to
>>>>> loadbalance it , I started another node.
>>>>>
>>>>> My expectation was that the counter should be in sync, i.e. if output
>>>> from
>>>>> one machine is key, 100 and another machine should read this and the
>>>> value
>>>>> should be key, 101.
>>>>> But, that didnt happened. Instead, on machine 2, the counter started
>>>> with 1.
>>>>>
>>>>>
>>>>> Regards,
>>>>> -Sameer.
>>>>>
>>>>
>>>>
>>>
>>
