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Posted to issues@flink.apache.org by "Tzu-Li (Gordon) Tai (JIRA)" <ji...@apache.org> on 2017/08/10 05:16:03 UTC
[jira] [Created] (FLINK-7407) Assumption of partition id strict
contiguity is too naive in Kafka consumer's AbstractPartitionDiscoverer
Tzu-Li (Gordon) Tai created FLINK-7407:
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Summary: Assumption of partition id strict contiguity is too naive in Kafka consumer's AbstractPartitionDiscoverer
Key: FLINK-7407
URL: https://issues.apache.org/jira/browse/FLINK-7407
Project: Flink
Issue Type: Improvement
Components: Kafka Connector
Reporter: Tzu-Li (Gordon) Tai
Fix For: 1.4.0
In the Kafka Consumer's {{AbstractPartitionDiscoverer}}, for partition discovery, already discovered partitions are tracked with the following map:
```
Map<String, Integer> topicsToLargestDiscoveredPartitionId
```
Simply put, on each discovery attempt's metadata fetch, all partition ids of a given topic that are smaller than the largest seen id will be ignored and not assigned. This approach lies on the assumption that fetched partition ids of a single topic are always strictly contiguous starting from 0.
This assumption may be too naive, in that partitions which were temporarily unavailable at the time of a discovery would be shadowed by available partitions with larger ids, and from then on would be left unassigned.
We should redesign how the `AbstractPartitionDiscoverer` tracks discovered partitions by not relying on the contiguity assumption, and also add test cases for non-contiguous fetched partition ids.
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