这异常是什么原因，引起，要如何解决，

这异常是什么原因，引起，要如何解决，能否在线QQ帮助我解决！！
QQ：81832527，我把代码发给你信息: Initializing, config='org.apache.struts.taglib.html.LocalStrings', returnNull=true
java.util.ConcurrentModificationException
        at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:448)
        at java.util.AbstractList$Itr.remove(AbstractList.java:433)
        at java.util.AbstractCollection.remove(AbstractCollection.java:255)
        at org.apache.coyote.RequestGroupInfo.removeRequestProcessor(RequestGroupInfo.java:17)
        at org.apache.coyote.RequestInfo.setGlobalProcessor(RequestInfo.java:96)
        at org.apache.coyote.http11.Http11Protocol$MXPoolListener.threadEnd(Http11Protocol.java:620)
        at org.apache.tomcat.util.threads.ThreadPool.removeThread(ThreadPool.java:279)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:727)
        at java.lang.Thread.run(Thread.java:534)java.util.ConcurrentModificationException
        at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:448)
        at java.util.AbstractList$Itr.next(AbstractList.java:419)
        at java.util.AbstractCollection.remove(AbstractCollection.java:254)
        at org.apache.coyote.RequestGroupInfo.removeRequestProcessor(RequestGroupInfo.java:17)
        at org.apache.coyote.RequestInfo.setGlobalProcessor(RequestInfo.java:96)
        at org.apache.coyote.http11.Http11Protocol$MXPoolListener.threadEnd(Http11Protocol.java:620)
        at org.apache.tomcat.util.threads.ThreadPool.removeThread(ThreadPool.java:279)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:727)
        at java.lang.Thread.run(Thread.java:534)