>
> I'm having an issue with using NRT and Tax. After a couple of days of
> running continuously , the taxonomyreader doesn't return results anymore
> (but taxindex has them).


Taxonomy Reader does not support NRT - see
https://issues.apache.org/jira/browse/LUCENE-3441 ("Add NRT support to
TaxonomyReader").

However I assume you are aware this since you commented on that issue.
So perhaps I did not understand the exact problem you are having.
Do you mean you refreshed the taxonomy reader but it did not "see" the new
categories?
Note that at the moment, since it does not support NRT, you need to first
commit() the taxonomy writer.
Is this the case?

If this does not explain the behavior you are seeing, a short code snippet
that demo it would be good, or, for the least, a description of the
sequence of operations that take place.


> How can i debug this?! does taxonomy index have a
> logoutput like indexwriter has? will that be enough or relevant?
>

Not a conveneient one. But there is some way. Far from perfect.
There is an extension point that allows you to control how the taxonomy
writer opens its internal index writer.
The method openIndexWriter(Directory directory, OpenMode openMode) is
protected.
So one can override it and open an index writer in a way that enabled some
info logging.

However there are at least two issues with this:
1) the info would be in the lower level of the internal index writer, and
not in that of the categories logic.
2) one cannot just call super.openIndexWriter(directory, openMode) and
modify the result before returning it, because once IW is opened it already
extracted its settings from IndexWriterConfig, and the infoStream for
example is final.

To workaround 2 above uou could take a look at the code of current
openIndexWriter(Directory directory, OpenMode openMode) implementation,
copy it to your extending class, and just modify the IWC to set the info
stream.

I opened https://issues.apache.org/jira/browse/LUCENE-3596 to track this.

Doron