Review Board 1.7.22


replicas may not have consistent data after becoming follower

Review Request #15938 - Created Dec. 1, 2013 and updated

Jun Rao
KAFKA-1154
Reviewers
kafka
kafka
kafka-1154; fix 1

 
Total:
2
Open:
2
Resolved:
0
Dropped:
0
Status:
From:
Ship it!
Posted (Dec. 2, 2013, 6:10 a.m.)

   

  
Could we add a comment why replicaId >= 0 means it is from a follower?
Posted (Dec. 2, 2013, 4:55 p.m.)

   

  
We had added the ability for a special consumer to read the replica log for troubleshooting. This patch takes that convenience away. We should probably look for another way to prevent the replica verification tool from giving false negatives. Can it use a different consumer id?
  1. We could add another debugging consumer mode so that it can read beyond HW. This will complicate the broker side logic a bit though. Also, reading beyond HW always has the danger that the fetched data is garbage since it's truncated. Perhaps we can wait and see if this new mode is really needed?
  2. Yes, we can probably wait. So, if the debugging consumer also reads upto the HW, just like a normal consumer, do we need to have a special "debugging consumer" ?
  3. Hmm.. so debugging consumer will be useful to read from replicas, which ordinary consumers can't do. We can probably address the debugging consumer properly in the future if/when we find use for reading beyond the HW. Rest of the patch looks good.
Do we still need this "TODO: the above may need to be fixed later" ?
  1. Yes, this can be removed.
Ship it!
Posted (Dec. 2, 2013, 9:39 p.m.)
Ship It!