Spring promoting request scoped bean to child threads (HttpServletRequest)

Question

I tried a lot of things now but i seem to miss a piece of the puzzle. Here is the story: I have a request scoped bean that reads some SessionContext from the HttpServletRequest.

Answer 1

For any future adventurers:

I took some time to dig through the Spring code and found RequestContextHolder that has a inheritableRequestAttributesHolder. If you look at the documentation of what that is (inheriting from: InheritableThreadLocal) one can read the following:

Inheritable thread-local variables are used in preference to ordinary thread-local variables when the per-thread-attribute being maintained in the variable (e.g., User ID, Transaction ID) must be automatically transmitted to any child threads that are created.

So the RequestContextHolder has a field for that and actually setRequestAttributes supports a flag to use inheritableRequestAttributesHolder. Furthermore if you look at RequestContextListener -> requestInitialized you find that it is called without the flag (= false). So what I ended up doing is this:

public class InheritableRequestContextListener extends RequestContextListener {
    private static final String REQUEST_ATTRIBUTES_ATTRIBUTE =
        InheritableRequestContextListener.class.getName() + ".REQUEST_ATTRIBUTES";

    @Override
    public void requestInitialized(ServletRequestEvent requestEvent) {
        if (!(requestEvent.getServletRequest() instanceof HttpServletRequest)) {
            throw new IllegalArgumentException(
                    "Request is not an HttpServletRequest: " + requestEvent.getServletRequest());
        }
        HttpServletRequest request = (HttpServletRequest) requestEvent.getServletRequest();
        ServletRequestAttributes attributes = new ServletRequestAttributes(request);
        request.setAttribute(REQUEST_ATTRIBUTES_ATTRIBUTE, attributes);
        LocaleContextHolder.setLocale(request.getLocale());
        RequestContextHolder.setRequestAttributes(attributes, true);
    }
}

And voila, I can access SessionContextProvider in child threads.