Hi Sungwoo, I think your approach works with current architecture of Celeborn, and interpreting IOException when reading as read failure makes sense. Currently only when CommitFiles fails will LifecycleManager announce data lost.
Thanks, Keyong Zhou Sungwoo Park <o...@pl.postech.ac.kr> 于2023年9月29日周五 22:05写道： > > Since the partition split has a good chance to contain data from almost > all > > upstream > > mapper tasks, the cost of re-computing all upstream tasks may have little > > difference > > to re-computing the actual mapper tasks in most cases. Of course it's not > > always true. > > > > To change from 'complete' to 'incomplete' also needs to refactor Worker's > > logic, which > > currently assumes that the succeeded attempts will not be changed after > > final committing > > files. > > > >> a subset of succeeded attempts. In Erik's proposal, the whole upstream > >> stage will be rerun when data lost. > > Thank you for your response --- things are now much clearer. > > From your comments shown above, let me assume that: > > 1. The whole upstream stage is rerun in the case of read failure. > > 2. Currently it is not easy to change the state of a shuffleId from > 'complete' to 'incomplete'. > > Then, for Celeborn-MR3, I would like to experiment with the following > approach: > > 1. If read failures occur for shuffleId #1, we pick up a new shuffleId > #2. > > 2. The upstream stage (or Vertex in the case of MR3) re-executes all tasks > again, but writes the output to shuffleId #2. > > 3. Tasks in the downstream stage re-try by reading from shuffleId #2. > > Do you think this approach makes sense under the current architecture of > Celeborn? If this approach is feasible, MR3 only needs to be notified of > read failures due to lost data by Celeborn ShuffleClient. Or, we could > just interpret IOException from Celeborn ShuffleClient as read failures, > in which case we can implement stage recompute without requiring any > extension of Celeborn. (However, it would be great if Celeborn > ShuffleClient could announce lost data explicitly.) > > An industrial user of Hive-MR3-Celeborn is trying hard to save disk usage > on Celeborn workers (which use SSDs of limited capacity), so stage > recompute would be a great new feature to them. > > Thank you, > > --- Sungwoo > > >
