unable to delete some files in build/web/WEB-INF/lib

How do I resolve this issue in Netbeans?

Warning: unable to delete some files in build/web/WEB-INF/lib - they 开发者_StackOverfloware probably locked by the J2EE server. 

Ted

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I use unlocker on the locked files to find out which process is locking them. Then, I kill those hanging processes if I can't stop them within NetBeans or on the App/Web server.