[jira] [Created] (SLING-7813) SlingHttpServletResponseImpl should log when setStatus is called after it is committed

["Julian Sedding (JIRA)" <ji...@apache.org>]

Julian Sedding created SLING-7813:
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             Summary: SlingHttpServletResponseImpl should log when setStatus is called after it is committed
                 Key: SLING-7813
                 URL: https://issues.apache.org/jira/browse/SLING-7813
             Project: Sling
          Issue Type: Improvement
          Components: Engine
    Affects Versions: Engine 2.6.12
            Reporter: Julian Sedding
            Assignee: Julian Sedding


I have been debugging a scenario, where a response did not have the (in this case) expected status code {{500}} set by an error handling script, but instead the status code was {{200}}.

It turns out that a rendering script calls {{#flushBuffer()}} on the response early on in order to optimize user experience. Later in the rendering chain a JSP causes a {{NullPointerException}}, triggering an error handler which calls {{#setStatus(500)}}. The {{#setStatus}} call is silently ignored.

"Fixing" this problem would require buffering the entire response and ignoring any flush calls (be it {{#flushBuffer()}}, {{#getWriter().flush()}} or {{#getOutputStream().flush()}}). This would be a change in behaviour, a violation of the Servlet spec and performance issues waiting to happen. Thus I am ruling out this option.

However, it would be helpful to improve "debuggability" of the problem. I propose to log a warning when {{#setStatus()}} is called. Additionally, if debug logging is enabled, I propose to log a stack trace to identify where the flush call originated (unless the flush was due to too many bytes written, which is not very helpful information).

cc [~rombert]




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