[LUCENE-2620] Queries with too many asterisks causing 100% CPU usage

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.1
• Fix Version/s: 2.9.4, 3.0.3, 3.1
• Component/s: core/search

Environment

Debian Lenny with Tomcat 5.5 and Mac OS X 10.6 with Tomcat 6, probably others

• Lucene Fields: New, Patch Available
• Assignee: Robert Muir
• Reporter: Nick Barkas
• Created: 24/Aug/10 16:32
• Updated: 27/Aug/24 15:35
• Resolved: 24/Aug/10 19:32

Description

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.