严重: The web application [/qdgswx] created a ThreadLocal with key of type [org.apache.log4j.helpers.ThreadLocalMap] (value [org .apache.log4j.helpers.ThreadLocalMap@4eb2bb3d]) and a value of type [java.util.Hashtable] (value [{logtype=11, nsrsbh=117474X, openid=-gKek}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
环境为：log4j-1.2.16,tomcat-6.0.37
这是Log4j-1.2.16的一个Bug,详见：https://bz.apache.org/bugzilla/show_bug.cgi?id=50486
解决方法：将Log4j换成1.2.17版就不会报以上异常。
下载地址：http://www.apache.org/dyn/closer.cgi/logging/log4j/1.2.17/log4j-1.2.17.tar.gz
Log4j MDC Tomcat下报异常org.apache.log4j.helpers.ThreadLocalMap
原文：http://www.cnblogs.com/yshyee/p/4355661.html