The behavior in case of error is likely undefined, so I'm not entirely surprised it's behaving this way. There may be things we can do to try to handle errors more gracefully for user initiated compactions when an iterator throws an exception, but it's definitely a good idea to write custom iterators in a way that tries to handle its own errors as much as possible.
On Wed, Jul 6, 2022, 20:42 Logan Jones <lo...@codescratch.com> wrote: > Thanks Chris for the quick reply. I'll explain the behavior I'm seeing, and > then maybe you all could either confirm this is the intended behavior, or > decide it's maybe not that great. > > My understanding of the happy case for running a user-initiated compaction > is that a fate/transaction gets created in zookeeper, and the Accumulo > master node ends up farming off the compactions to the correct tablet > servers, once the tablets have been completed, somehow the > fates/transactions in zookeeper get cleaned up. > > I experienced a problem, however, in the unhappy case for compactions which > I have since reproduced. We had a custom iterator configured for a table, > and that custom iterator was in a bad state (i.e. it was always throwing an > exception during initialization). What we noticed is that the fates are > indefinitely stuck IN_PROGRESS and never go away in this case. Effectively > we have a poison pill, and if you issue too many compactions against that > table, you can cause other bad problems. > > I created a repo to demonstrate the problem as succinctly as I could > manage: > > https://github.com/loganasherjones/accumulo-iterator-failures > > I thought initially that maybe it was due to the fact that our iterator was > throwing an error during initialization, but this appears to be happening > for any error on next, seek, or init calls. > > So my questions are > > 1. Is it expected that a failure in a seek, next, or init in an iterator > during a user-initiated compaction would cause accumulo to non-stop retry > the compaction > 2. If so, could you help me understand why? > > Thanks in advance, > > - Logan > > > > On Wed, Jul 6, 2022 at 6:31 PM Christopher <ctubb...@apache.org> wrote: > > > Yes, either here (especially if it's related to a bug or proposed code > > change) or at user@ would work, if it's more of a user question. Here is > > fine if you're not sure. > > > > On Wed, Jul 6, 2022, 16:35 Logan Jones <lo...@codescratch.com> wrote: > > > > > Hello: > > > > > > I would like to discuss what happens when iterators cause > user-initiated > > > compactions to fail, specifically in relation to the fate transactions. > > Is > > > this the right list for this discussion? > > > > > > Thanks, > > > > > > - Logan > > > > > >
