So you are creating 10 (or 200?) parsers every second? As you can imagine,
creating new parsers is really expensive. Is it possible for you to cache
the parser created by the previous JSP invocation? (Implementing a parser
pool, for example.)
Thanks,
Sandy Gao
Software Developer, IBM Canada
(1-905) 413-3255
[EMAIL PROTECTED]
"Cameron Hart"
<[EMAIL PROTECTED] To: <[EMAIL PROTECTED]>
a.govt.nz> cc:
Subject: Xerces-2 DOMParser
bottleneck
03/19/2003 12:42
AM
Please respond to
xerces-j-user
I'm running a servlet under tomcat that DOM parses a couple of xml docs,
grabs relevant nodes and serializes the new doc into xhtml output. I
have found a bottleneck (or deadlock?) when the servlet is under load.
The bottleneck can easily be demonstrated by running a load test against
the attached jsp. We use OpenSTA to test with 20 VU's requesting the
page every 1/10th of a second. If you do a thread dump after the CPU has
been sitting at 100% you should say many of the threads are at
org.apache.xerces.impl.dv.DTDDVFactory.getInstance - waiting to lock.
This behaviour is killing our webapp under not much load (a lot less
load that we ran our test at).
Is this a problem with Xerces? Is there something we can do to avoid
this behaviour? We were thinking about creating a pool of DOMParser
objects and see if that helps.
The following are the thread dumps that is locked and one of the
waiting thread. Attached is a jsp and an html page we used to replicate
the problem.
"Thread-46" daemon prio=5 tid=0x1836D8E0 nid=0xbcc waiting on condition
[1ac4e000..1ac4fdc0]
at java.lang.StringBuffer.expandCapacity(StringBuffer.java:202)
at java.lang.StringBuffer.append(StringBuffer.java:392)
- locked <02AF19A0> (a java.lang.StringBuffer)
at
org.apache.catalina.loader.StandardClassLoader.toString(StandardClassLoader.java:571)
at
org.apache.catalina.loader.WebappClassLoader.toString(WebappClassLoader.java:906)
at java.lang.String.valueOf(String.java:2177)
at java.lang.StringBuffer.append(StringBuffer.java:361)
- locked <02AF19D0> (a java.lang.StringBuffer)
at org.apache.xerces.util.ObjectFactory.newInstance(Unknown Source)
at org.apache.xerces.impl.dv.DTDDVFactory.getInstance(Unknown Source)
- locked <12D15BC0> (a java.lang.Class)
at org.apache.xerces.impl.dv.DTDDVFactory.getInstance(Unknown Source)
- locked <12D15BC0> (a java.lang.Class)
at
org.apache.xerces.parsers.DTDConfiguration.createDatatypeValidatorFactory(Unknown
Source)
at org.apache.xerces.parsers.DTDConfiguration.<init>(Unknown Source)
at org.apache.xerces.parsers.StandardParserConfiguration.<init>(Unknown
Source)
at
org.apache.xerces.parsers.IntegratedParserConfiguration.<init>(Unknown
Source)
at
org.apache.xerces.parsers.IntegratedParserConfiguration.<init>(Unknown
Source)
at sun.reflect.GeneratedConstructorAccessor15.newInstance(Unknown
Source)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
at java.lang.Class.newInstance0(Class.java:306)
at java.lang.Class.newInstance(Class.java:259)
at org.apache.xerces.util.ObjectFactory.newInstance(Unknown Source)
at org.apache.xerces.util.ObjectFactory.findJarServiceProvider(Unknown
Source)
at org.apache.xerces.util.ObjectFactory.createObject(Unknown Source)
at org.apache.xerces.util.ObjectFactory.createObject(Unknown Source)
at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
at org.apache.xerces.jaxp.DocumentBuilderImpl.<init>(Unknown Source)
at
org.apache.xerces.jaxp.DocumentBuilderFactoryImpl.newDocumentBuilder(Unknown
Source)
at
org.apache.jsp.domparser_0002dlock_jsp.
_jspService(domparser_0002dlock_jsp.java:64)
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:204)
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(ApplicationFilterChain.java:247)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:260)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(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:2407)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(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.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:261)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:360)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:632)
at
org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:590)
at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:707)
at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:530)
at java.lang.Thread.run(Thread.java:536)
"Thread-45" daemon prio=5 tid=0x183F4DC8 nid=0xd70 waiting for monitor
entry [1ac0f000..1ac0fdc0]
at org.apache.xerces.impl.dv.DTDDVFactory.getInstance(Unknown Source)
- waiting to lock <12D15BC0> (a java.lang.Class)
at
org.apache.xerces.parsers.DTDConfiguration.createDatatypeValidatorFactory(Unknown
Source)
at org.apache.xerces.parsers.DTDConfiguration.<init>(Unknown Source)
at org.apache.xerces.parsers.StandardParserConfiguration.<init>(Unknown
Source)
at
org.apache.xerces.parsers.IntegratedParserConfiguration.<init>(Unknown
Source)
at
org.apache.xerces.parsers.IntegratedParserConfiguration.<init>(Unknown
Source)
at sun.reflect.GeneratedConstructorAccessor15.newInstance(Unknown
Source)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
at java.lang.Class.newInstance0(Class.java:306)
at java.lang.Class.newInstance(Class.java:259)
at org.apache.xerces.util.ObjectFactory.newInstance(Unknown Source)
at org.apache.xerces.util.ObjectFactory.findJarServiceProvider(Unknown
Source)
at org.apache.xerces.util.ObjectFactory.createObject(Unknown Source)
at org.apache.xot
org.apache.catalina.erces.util.ObjectFactory.createObject(Unknown
Source)
at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source)
at org.apache.xerces.jaxp.DocumentBuilderImpl.<init>(Unknown Source)
at
org.apache.xerces.jaxp.DocumentBuilderFactoryImpl.newDocumentBuilder(Unknown
Source)
at
org.apache.jsp.domparser_0002dlock_jsp.
_jspService(domparser_0002dlock_jsp.java:64)
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:204)
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(ApplicationFilterChain.java:247)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:260)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(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.java:191)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2407)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at
org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(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$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at
org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
at
org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:261)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:360)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:632)
at
org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:590)
at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:707)
at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:530)
at java.lang.Thread.run(Thread.java:536)
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#### index.html has been removed from this note on March 19 2003 by Sandy
Gao
#### domparser-lock.jsp has been removed from this note on March 19 2003 by
Sandy Gao
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