KafkaConsumerBase

[aitozi <gj...@gmail.com>]

Hi,

i have a question that , when we use KafkaConsumerBase, we will have to
fetch data from different partition  
 in different parllel thread like the method shown in 
KafkaConsumerBase.java (version 1.2.0)

	protected static List<KafkaTopicPartition> assignPartitions(
			List<KafkaTopicPartition> allPartitions,
			int numConsumers, int consumerIndex) {
		final List<KafkaTopicPartition> thisSubtaskPartitions = new ArrayList<>(
				allPartitions.size() / numConsumers + 1);

		for (int i = 0; i < allPartitions.size(); i++) {
			if (i % numConsumers == consumerIndex) {
				thisSubtaskPartitions.add(allPartitions.get(i));
			}
		}
		
		return thisSubtaskPartitions;
	}

but i have not find any place invoke this method ,  in
KafkaConsumerThread.java it used 

consumerCallBridge.assignPartitions(consumer,
convertKafkaPartitions(subscribedPartitions));

i think here subscribedPartitions is all the partitions , not
subtaskPartitions.  Can any one address my problem



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Re: KafkaConsumerBase

[aitozi <gj...@gmail.com>]

Hi,Gordon

    Yes, just now i again read the code in assignTopicPartitions method , it
indeed subscribe the partition the subtask should subscribe to. i  didn't
read the for loop generate subscribedPartitions for each subtasks in
assignTopicPartitions carefully before 

for (int i = getRuntimeContext().getIndexOfThisSubtask(); i <
kafkaTopicPartitions.size(); i +=
getRuntimeContext().getNumberOfParallelSubtasks()) {
				subscribedPartitions.add(kafkaTopicPartitions.get(i));	}

you ar right : "the partitions are still filtered out to only be the
partitions for each local subtask, using the `assignTopicPartitions` method"

Thanks
aitozi



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Re: KafkaConsumerBase

["Tzu-Li (Gordon) Tai" <tz...@apache.org>]

Hi!

method shown in KafkaConsumerBase.java (version 1.2.0) 

A lot has changed in the FlinkKafkaConsumerBase since version 1.2.0.
And if I remember correctly, the `assignPartitions` method was actually a no longer relevant method used in the code, and was properly removed afterwards.
The method for partition assigning in 1.2.0 is called `assignTopicPartitions`, and is used in the open() method.

consumerCallBridge.assignPartitions(consumer, 
convertKafkaPartitions(subscribedPartitions)); 

i think here subscribedPartitions is all the partitions , not 
subtaskPartitions.
This code snippet is from `KafkaConsumerThread`, correct?

As stated above, the partitions are still filtered out to only be the partitions for each local subtask, using the `assignTopicPartitions` method. So here, the `subscribedPartitions` is not the complete list of partitions, only the partitions that the subtask should subscribe to.


Cheers,
Gordon

On 2 August 2017 at 9:52:03 PM, aitozi (gjying1314@gmail.com) wrote:


Hi,  

i have a question that , when we use KafkaConsumerBase, we will have to  
fetch data from different partition  
in different parllel thread like the method shown in  
KafkaConsumerBase.java (version 1.2.0)  

protected static List<KafkaTopicPartition> assignPartitions(  
List<KafkaTopicPartition> allPartitions,  
int numConsumers, int consumerIndex) {  
final List<KafkaTopicPartition> thisSubtaskPartitions = new ArrayList<>(  
allPartitions.size() / numConsumers + 1);  

for (int i = 0; i < allPartitions.size(); i++) {  
if (i % numConsumers == consumerIndex) {  
thisSubtaskPartitions.add(allPartitions.get(i));  
}  
}  

return thisSubtaskPartitions;  
}  

but i have not find any place invoke this method , in  
KafkaConsumerThread.java it used  

consumerCallBridge.assignPartitions(consumer,  
convertKafkaPartitions(subscribedPartitions));  

i think here subscribedPartitions is all the partitions , not  
subtaskPartitions. Can any one address my problem  



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