[GitHub] [pulsar] codelipenghui commented on pull request #7106: Fixed ordering issue in KeyShared dispatcher when adding consumer

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codelipenghui commented on pull request #7106:
URL: https://github.com/apache/pulsar/pull/7106#issuecomment-636339953


   @merlimat If I understand correctly all consumers can't get new messages if a new consumer joined right? The messages will add to the redelivery queue will lead to the next read entry operation replay the redelivery queue so that new messages can't keep going. This may cause an increase in consumption latency for all consumers. But, I think most of the existing consumers can continue to consume new messages because they do not overlap with the newly added consumer in any hash range. 
   
   So in the #6977, I added a buffer for the messages that need to wait for mark delete position processed. This can minimize the consumption latency jitter caused by the newly added consumer especially when consumers are hungry. This will be more useful for e2e latency-sensitive scenes. I want to listen to your thoughts, maybe my thoughts are more worrying.
   
   Other than that, I have no objections to this PR. And except added a buffer, I think #6977 is the same, #6977 added a field in the consumer named `fencePositionForKeyShared `. Essentially, equivalent to `recentlyJoinedConsumers` in this PR.


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