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https://issues.apache.org/jira/browse/SLING-7813?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17414837#comment-17414837
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Bertrand Delacretaz edited comment on SLING-7813 at 9/14/21, 11:49 AM:
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_Update: the below comment is not valid as it refers to sendError, which does
declare exceptions in the Servlet API, but setStatus does not_
I stumbled on this while looking at SLING-10810 and I think [commit
bc9696bd|https://github.com/apache/sling-org-apache-sling-engine/commit/bc9696bd4f52a3a2b50a19f2572b80a4ac2ea3a2]
introduces a non-standard behavior, where setStatus just logs a message if the
request is already committed, instead of throwing an exception like
[HttpServletResponse.sendError|https://javaee.github.io/javaee-spec/javadocs/javax/servlet/http/HttpServletResponse.html#sendError-int-java.lang.String-]
does.
Actually, IIUC that non-standard behavior only happens if setStatus(status,
message) is called with a non-empty message, otherwise super.setStatus is
called.
That's suboptimal IMO, but considering that these changes are more than 3 years
old now there's probably no urgent need to change that back - I'll just leave
that note here in case we want to revisit this in the future.
was (Author: bdelacretaz):
I stumbled on this while looking at SLING-10810 and I think [commit
bc9696bd|https://github.com/apache/sling-org-apache-sling-engine/commit/bc9696bd4f52a3a2b50a19f2572b80a4ac2ea3a2]
introduces a non-standard behavior, where setStatus just logs a message if the
request is already committed, instead of throwing an exception like
[HttpServletResponse.sendError|https://javaee.github.io/javaee-spec/javadocs/javax/servlet/http/HttpServletResponse.html#sendError-int-java.lang.String-]
does.
Actually, IIUC that non-standard behavior only happens if setStatus(status,
message) is called with a non-empty message, otherwise super.setStatus is
called.
That's suboptimal IMO, but considering that these changes are more than 3 years
old now there's probably no urgent need to change that back - I'll just leave
that note here in case we want to revisit this in the future.
> 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
> Priority: Minor
> Fix For: Engine 2.6.14
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> 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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