Under some circonstances, tomcat owns two file handles per jar in WEB-INF/lib/

sudo lsof -u tomcat|grep xwiki-commons-xml                    
java    13840 tomcat  mem    REG                9,2    71062 90972820 /usr/local/winesquare-2012-09-24-1516/WEB-INF/lib/xwiki-commons-xml-3.5.1.jar
java    13840 tomcat  318r   REG                9,2    71062 90972820 /usr/local/winesquare-2012-09-24-1516/WEB-INF/lib/xwiki-commons-xml-3.5.1.jar