Unknown error in XPath

[Cory Isaacson <ci...@compuflex.com>]

In running a transform, we occasionally get the error below. This is only
during a stress test, and happens perhaps once per several 100 transforms.
Any idea how we can determine what the problem is? We get a similar problem
(although not from a NullPointerException) in a different stylesheet as
well, so it doesn't seem to be tied to the stylesheet.

The application is performing the transforms in a thread-safe manner, by
caching the Templates object and getting a new transformer for each
invocation of the transform.

Any ideas are most appreciated.

Thanks,

Cory

javax.xml.transform.TransformerException: Unknown error in XPath.
 at org.apache.xpath.XPath.execute(XPath.java:334)
 at org.apache.xalan.templates.ElemVariable.getValue(ElemVariable.java:316)
 at org.apache.xalan.templates.ElemVariable.execute(ElemVariable.java:284)
 at
org.apache.xalan.templates.ElemForEach.transformSelectedNodes(ElemForEach.ja
va:423)
 at org.apache.xalan.templates.ElemForEach.execute(ElemForEach.java:284)
 at
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Transform
erImpl.java:2318)
 at org.apache.xalan.templates.ElemTemplate.execute(ElemTemplate.java:431)
 at
org.apache.xalan.templates.ElemCallTemplate.execute(ElemCallTemplate.java:27
4)
 at
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Transform
erImpl.java:2318)
 at
org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.java:
696)
 at
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Transform
erImpl.java:2318)
 at
org.apache.xalan.templates.ElemLiteralResult.execute(ElemLiteralResult.java:
696)
 at
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Transform
erImpl.java:2318)
 at org.apache.xalan.templates.ElemTemplate.execute(ElemTemplate.java:431)
 at
org.apache.xalan.templates.ElemCallTemplate.execute(ElemCallTemplate.java:27
4)
 at
org.apache.xalan.templates.ElemApplyTemplates.transformSelectedNodes(ElemApp
lyTemplates.java:425)
 at
org.apache.xalan.templates.ElemApplyTemplates.execute(ElemApplyTemplates.jav
a:215)
 at
org.apache.xalan.transformer.TransformerImpl.executeChildTemplates(Transform
erImpl.java:2318)
 at
org.apache.xalan.transformer.TransformerImpl.applyTemplateToNode(Transformer
Impl.java:2185)
 at
org.apache.xalan.transformer.TransformerImpl.transformNode(TransformerImpl.j
ava:1263)
 at
org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:
671)
 at
org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:
1179)
 at
org.apache.xalan.transformer.TransformerImpl.transform(TransformerImpl.java:
1157)
 at
com.compuflex.framework.gui.taglib.ControlGroupTag.doStartTag(ControlGroupTa
g.java:293)
 at
org.apache.jsp.vpSLVFrame_jsp._jspx_meth_fw_controlgroup_0(vpSLVFrame_jsp.ja
va:230)
 at org.apache.jsp.vpSLVFrame_jsp._jspService(vpSLVFrame_jsp.java:101)
 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:2
10)
 at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Application
FilterChain.java:247)
 at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterCh
ain.java:193)
 at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.ja
va:256)
 at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
 at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
 at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.ja
va:191)
 at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
 at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
 at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2416)
 at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180
)
 at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
 at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.
java:171)
 at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:641)
 at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172
)
 at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:641)
 at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
 at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java
:174)
 at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invok
eNext(StandardPipeline.java:643)
 at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
 at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
 at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
 at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:601)
 at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConne
ction(Http11Protocol.java:392)
 at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:565)
 at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.jav
a:619)
 at java.lang.Thread.run(Thread.java:536)
Caused by: java.lang.NullPointerException
---------
java.lang.NullPointerException

Cory Isaacson
Vice President Product Management
Quovadx, Inc.
(818) 884-1168
cory.isaacson@quovadx.com
www.quovadx.com