If a search query has many adjacent asterisks (e.g. fo**************obar), I can get my webapp caught in a loop that does not seem to end in a reasonable amount of time and may in fact be infinite. For just a few asterisks the query eventually does return some results, but as I add more it takes a longer and longer amount of time. After about six or seven asterisks the query never seems to finish. Even if I abort the search, the thread handling the troublesome query continues running in the background and pinning a CPU.
I found the problem in src/java/org/apache/lucene/search/WildcardTermEnum.java on Lucene 3.0.1 and it looks like 3.0.2 ought to be affected as well. I'm not sure about trunk, though. I have a patch that fixes the problem for me in 3.0.1.