I'm quite certain this shouldn't happen also when Commit wasn't called. Mike, can you comment on that?
On Thu, Jun 14, 2012 at 8:03 PM, Christopher Currens < currens.ch...@gmail.com> wrote: > Well, the only thing I see is that there is no place where writer.Commit() > is called in the delegate assigned to corpusReader.OnDocument. I know that > lucene is very transactional, and at least in 3.x, the writer will never > auto commit to the index. You can write millions of documents, but if > commit is never called, those documents aren't actually part of the index. > Committing isn't a cheap operation, so you definitely don't want to do it > on every document. > > You can test it yourself with this (naive) solution. Right below the > writer.SetUseCompoundFile(false) line, add "int numDocsAdded = 0;". At the > end of the corpusReader.OnDocument delegate add: > > // Example only. I wouldn't suggest committing this often > if(++numDocsAdded % 5 == 0) > { > writer.Commit(); > } > > I had the application crash for real on this file: > > http://dumps.wikimedia.org/gawiktionary/20120613/gawiktionary-20120613-pages-meta-history.xml.bz2 > , > about 20% into the operation. Without the commit, the index is empty. Add > it in, and I get 755 files in the index after it crashes. > > > Thanks, > Christopher > > On Wed, Jun 13, 2012 at 6:13 PM, Itamar Syn-Hershko <ita...@code972.com > >wrote: > > > Yes, reproduced in first try. See attached program - I referenced it to > > current trunk. > > > > > > On Thu, Jun 14, 2012 at 3:54 AM, Itamar Syn-Hershko <ita...@code972.com > >wrote: > > > >> Christopher, > >> > >> I used the IndexBuilder app from here > >> https://github.com/synhershko/Talks/tree/master/LuceneNeatThings with a > >> 8.5GB wikipedia dump. > >> > >> After running for 2.5 days I had to forcefully close it (infinite loop > in > >> the wiki-markdown parser at 92%, go figure), and the 40-something GB > index > >> I had by then was unusable. I then was able to reproduce this > >> > >> Please note I now added a few safe-guards you might want to remove to > >> make sure the app really crashes on process kill. > >> > >> I'll try to come up with a better way to reproduce this - hopefully Mike > >> will be able to suggest better ways than manual process kill... > >> > >> On Thu, Jun 14, 2012 at 1:41 AM, Christopher Currens < > >> currens.ch...@gmail.com> wrote: > >> > >>> Mike, The codebase for lucene.net should be almost identical to java's > >>> 3.0.3 release, and LUCENE-1044 is included in that. > >>> > >>> Itamar, are you committing the index regularly? I only ask because I > >>> can't > >>> reproduce it myself by forcibly terminating the process while it's > >>> indexing. I've tried both 3.0.3 and 2.9.4. If I don't commit at all > and > >>> terminate the process (even with a 10,000 4K documents created), there > >>> will > >>> be no documents in the index when I open it in luke, which I expect. > If > >>> I > >>> commit at 10,000 documents, and terminate it a few thousand after that, > >>> the > >>> index has the first ten thousand that were committed. I've even > >>> terminated > >>> it *while* a second commit was taking place, and it still had all of > the > >>> documents I expected. > >>> > >>> It may be that I'm not trying to reproducing it correctly. Do you > have a > >>> minimal amount of code that can reproduce it? > >>> > >>> > >>> Thanks, > >>> Christopher > >>> > >>> On Wed, Jun 13, 2012 at 9:31 AM, Michael McCandless < > >>> luc...@mikemccandless.com> wrote: > >>> > >>> > Hi Itamar, > >>> > > >>> > One quick question: does Lucene.Net include the fixes done for > >>> > LUCENE-1044 (to fsync files on commit)? Those are very important for > >>> > an index to be intact after OS/JVM crash or power loss. > >>> > > >>> > More responses below: > >>> > > >>> > On Tue, Jun 12, 2012 at 8:20 PM, Itamar Syn-Hershko < > >>> ita...@code972.com> > >>> > wrote: > >>> > > >>> > > I'm a Lucene.Net committer, and there is a chance we have a bug in > >>> our > >>> > > FSDirectory implementation that causes indexes to get corrupted > when > >>> > > indexing is cut while the IW is still open. As it roots from some > >>> > > retroactive fixes you made, I'd appreciate your feedback. > >>> > > > >>> > > Correct me if I'm wrong, but by design Lucene should be able to > >>> recover > >>> > > rather quickly from power failures or app crashes. Since existing > >>> segment > >>> > > files are read only, only new segments that are still being written > >>> can > >>> > get > >>> > > corrupted. Hence, recovering from worst-case scenarios is done by > >>> simply > >>> > > removing the write.lock file. The worst that could happen then is > >>> having > >>> > the > >>> > > last segment damaged, and that can be fixed by removing those > files, > >>> > > possibly by running CheckIndex on the index. > >>> > > >>> > You shouldn't even have to run CheckIndex ... because (as of > >>> > LUCENE-1044) we now fsync all segment files before writing the new > >>> > segments_N file, and then removing old segments_N files (and any > >>> > segments that are no longer referenced). > >>> > > >>> > You do have to remove the write.lock if you aren't using > >>> > NativeFSLockFactory (but this has been the default lock impl for a > >>> > while now). > >>> > > >>> > > Last week I have been playing with rather large indexes and crashed > >>> my > >>> > app > >>> > > while it was indexing. I wasn't able to open the index, and Luke > was > >>> even > >>> > > kind enough to wipe the index folder clean even though I opened it > in > >>> > > read-only mode. I re-ran this, and after another crash running > >>> CheckIndex > >>> > > revealed nothing - the index was detected to be an empty one. I am > >>> not > >>> > > entirely sure what could be the cause for this, but I suspect it > has > >>> > > been corrupted by the crash. > >>> > > >>> > Had no commit completed (no segments file written)? > >>> > > >>> > If you don't fsync then all sorts of crazy things are possible... > >>> > > >>> > > I've been looking at these: > >>> > > > >>> > > > >>> > > >>> > https://issues.apache.org/jira/browse/LUCENE-3418?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel > >>> > > > >>> > > >>> > https://issues.apache.org/jira/browse/LUCENE-2328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel > >>> > > >>> > (And LUCENE-1044 before that ... it was LUCENE-1044 that LUCENE-2328 > >>> > broke...). > >>> > > >>> > > And it seems like this is what I was experiencing. Mike and Mark > will > >>> > > probably be able to tell if this is what they saw or not, but as > far > >>> as I > >>> > > can tell this is not an expected behavior of a Lucene index. > >>> > > >>> > Definitely not expected behavior: assuming nothing is flipping bits, > >>> > then on OS/JVM crash or power loss your index should be fine, just > >>> > reverted to the last successful commit. > >>> > > >>> > > What I'm looking for at the moment is some advice on what > FSDirectory > >>> > > implementation to use to make sure no corruption can happen. The > 3.4 > >>> > version > >>> > > (which is where LUCENE-3418 was committed to) seems to handle a > lot > >>> of > >>> > > things the 3.0 doesn't, but on the other hand LUCENE-3418 was > >>> introduced > >>> > by > >>> > > changes made to the 3.0 codebase. > >>> > > >>> > Hopefully it's just that you are missing fsync! > >>> > > >>> > > Also, is there any test in the suite checking for those scenarios? > >>> > > >>> > Our test framework has a sneaky MockDirectoryWrapper that, after a > >>> > test finishes, goes and corrupts any unsync'd files and then verifies > >>> > the index is still OK... it's good because it'll catch any times we > >>> > are missing calls t sync, but, it's not low level enough such that if > >>> > FSDir is failing to actually call fsync (that wsa the bug in > >>> > LUCENE-3418) then it won't catch that... > >>> > > >>> > Mike McCandless > >>> > > >>> > http://blog.mikemccandless.com > >>> > > >>> > >> > >> > > >