[
https://issues.apache.org/jira/browse/KAFKA-1326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14157247#comment-14157247
]
Guozhang Wang commented on KAFKA-1326:
--------------------------------------
A couple of more points we have seen from the old consumer that needs to be
carefully addressed in the new consumer:
1. Memory management / decompression: in the old consumer, de-compression can
easily allocate a huge amount of memory within a very short time, we need to
add similar memory management as new producer to bound the memory usage, and at
the same time make sure that we do not allocate more memory than necessary
while doing the de-compression.
2. Max fetch size: since the old consumer's max fetch size is fixed by a
config, it as a result requires the similar config on the broker / producer. It
should be easy to let the new consumer dynamically increase its max fetch size
when receiving a single partial message so we can get rid of the new messages.
3. Problems with consumer iterator: today's consumer iterator has several
inconsistencies with the Java iterator principles, for example KAFKA-520, and
that exception thrown while de-serializing the message will cause it to be
skipped since iter.next() has already been called, etc. Although we are not
going with the stream-based API in the new consumer but instead use a
non-blocking pooling model, we need to make sure these usage pattern issues are
not carried in the new API.
> New consumer checklist
> ----------------------
>
> Key: KAFKA-1326
> URL: https://issues.apache.org/jira/browse/KAFKA-1326
> Project: Kafka
> Issue Type: New Feature
> Components: consumer
> Affects Versions: 0.9.0
> Reporter: Neha Narkhede
> Assignee: Neha Narkhede
> Labels: feature
>
> We will use this JIRA to track the list of issues to resolve to get a working
> new consumer client. The consumer client can work in phases -
> 1. Add new consumer APIs and configs
> 2. Refactor Sender. We will need to use some common APIs from Sender.java
> (https://issues.apache.org/jira/browse/KAFKA-1316)
> 3. Add metadata fetch and refresh functionality to the consumer (This will
> require https://issues.apache.org/jira/browse/KAFKA-1316)
> 4. Add functionality to support subscribe(TopicPartition...partitions). This
> will add SimpleConsumer functionality to the new consumer. This does not
> include any group management related work.
> 5. Add ability to commit offsets to Kafka. This will include adding
> functionality to the commit()/commitAsync()/committed() APIs. This still does
> not include any group management related work.
> 6. Add functionality to the offsetsBeforeTime() API.
> 7. Add consumer co-ordinator election to the server. This will only add a new
> module for the consumer co-ordinator, but not necessarily all the logic to do
> group management.
> At this point, we will have a fully functional standalone consumer and a
> server side co-ordinator module. This will be a good time to start adding
> group management functionality to the server and consumer.
> 8. Add failure detection capability to the consumer when group management is
> used. This will not include any rebalancing logic, just the ability to detect
> failures using session.timeout.ms.
> 9. Add rebalancing logic to the server and consumer. This will be a tricky
> and potentially large change since it will involve implementing the group
> management protocol.
> 10. Add system tests for the new consumer
> 11. Add metrics
> 12. Convert mirror maker to use the new consumer.
> 13. Convert perf test to use the new consumer
> 14. Performance testing and analysis.
> 15. Review and fine tune log4j logging
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
