Is there a way to avoid the bottleneck in Jaxp13XPathExpression when using XPath?

I am converting a Spring managed orchestration service to use Spring Integration as a proof of concept.

I have the basic app running, but have encountered a major bottleneck.

The app uses an inbound gateway to take an XML payload from the standard MultivaluedMap:

<int-http:inbound-gateway id="DSOWebServicePOC" request-channel="httpRequestsChannel" 
    reply-channel="httpResponsesChannel" path="/orchestrate/do" supported-methods="POST" 
    payload-expression="#requestParams.getFirst(&quot;XML&quot;)"> 
</int-http:inbound-gateway>

This is then sent via a direct channel to an xpath-splitter designed to break the request (which containts many similar sub-requests) down into each actual request that can be processed.

The performance of the application was about 6 times slower than the original service, and it is due to the method org.springframework.xml.xpath.Jaxp13XPathExpressionFactory$Jaxp13XPathExpression.evaluate(Node, QName)

This is because compiled XPath expressions are not thread safe, and the method in Jaxp13XPathExpression has a synchronized block - combined with Spring using singletons... In the original service, I used a thread local containing the complied XPathExressions.

I have tried custom scopes to no avail, and this explains why

Custom Spring Scope not working for Message Channel

I have followed the example for dynamic ftp, but use the thread name as the map key. I have combined this with a child application context containing the incoming channel, the splitter and the xpath-expression, but in the code, the channel resolver gets the bean by name from the new context:

http://ift.tt/1DTA25D

I cannot do this for the XPathExpression as Jaxp13XPathExpression is a private static class within an abstract class with default access modifier.

How can I get a compiled XPathExpression with a different scope - whether it is request/session/thread, without just creating a service activator with a thread local and just not using the build in XML handling of the framework?

Further info:

Router:

<int:router input-channel="httpRequestsChannel" ref="channelResolver" method="resolve" />

Resolve Method:

public MessageChannel resolve() {
        String thread = Thread.currentThread().getName();
        ChannelResolverIntegrationBeans beans = this.integrationBeans
                .get(thread);
        if (beans == null) {
            beans = createNewThreadIntegrationBeans(thread);
        }
        return beans.getChannel();
    }

ChannelResolverIntegrationBeans method - the XPathExpression was my last attempt to get it to work, but it returns

Bean named 'dsoBatchRequestXPathNs' must be of type [javax.xml.xpath.XPathExpression], but was actually of type [org.springframework.xml.xpath.Jaxp13XPathExpressionFactory$Jaxp13XPathExpression]

private synchronized ChannelResolverIntegrationBeans createNewThreadIntegrationBeans(
        String thread) {
    ChannelResolverIntegrationBeans beans = this.integrationBeans
            .get(thread);
    if (beans == null) {
        ConfigurableApplicationContext ctx = new ClassPathXmlApplicationContext(
                new String[] { "/xmlChildHandlerContext.xml" }, this.appContext);
        MessageChannel channel = ctx.getBean("fromDynamicRouter",
                MessageChannel.class);
        EventDrivenConsumer splitter = ctx.getBean("requestSplitter",
                EventDrivenConsumer.class);
    XPathExpression expression = ctx.getBean("dsoBatchRequestXPathNs",
            XPathExpression.class);
        beans = new ChannelResolverIntegrationBeans(channel, splitter);
        this.integrationBeans.put(thread, beans);
        // Will works as the same reference is presented always
        this.contexts.put(beans, ctx);
    }
    return beans;
}

Child context beans:

<int:channel id="fromDynamicRouter" />

<int-xml:xpath-splitter id="requestSplitter"
    input-channel="fromDynamicRouter" output-channel="xPathSplitterResultsChannel"
    xpath-expression-ref="dsoBatchRequestXPathNs">
</int-xml:xpath-splitter>

<int-xml:xpath-expression id="dsoBatchRequestXPathNs"
    expression="/dso:DsoRequests/dso:DsoRequest/*" namespace-map="namespaceMap" />