Software caused connection abort: socket write error

I use Apache as proxy to dispatch client requests to Weblogic Server
The exception below appeared sometimes in Weblogic Domain log file.
What does the IOException "Software caused connection abort: socket write error
" mean?
Is this a bug in struts
(org.apache.struts.taglib.tiles.InsertTag.java) or Weblogic?

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javax.servlet.jsp.JspException: Can't insert page 'layout.jsp' : Software caused connection abort: socket write error
at org.apache.struts.taglib.tiles.InsertTag$InsertHandler.processException(InsertTag.java:956)
at org.apache.struts.taglib.tiles.InsertTag$InsertHandler.doEndTag(InsertTag.java:884)
at org.apache.struts.taglib.tiles.InsertTag.doEndTag(InsertTag.java:473)
at jsp_servlet._awb.__assign._jspService(__assign.java:219)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:33)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:971)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:402)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:305)
at weblogic.servlet.internal.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:307)
at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1069)
at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:455)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:279)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at weblogic.servlet.internal.ServletStubImpl$ServletInvocationAction.run(ServletStubImpl.java:971)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:402)
at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:28)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
at com.ann.util.encodingFilter.doFilter(encodingFilter.java:39)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:27)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:6356)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:317)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:118)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3635)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2585)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)