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From Mark Thomas <ma...@apache.org>
Subject Re: Intermittent JSP Caching/Compiling Issue while under load
Date Thu, 07 Nov 2019 11:40:26 GMT
On 06/11/2019 20:04, Mark Thomas wrote:
> I've found the root cause.
> 
> When checking the timestamps of JSPs, the JSP engine (because it has to
> access all resources via the Servlet API) requests a URL for the JSP,
> opens a connection to the URL and then checks the last modified time.
> This goes directly to the on-disk file.
> 
> When reading the content, the request goes via the static resource cache
> because we can intercept the call to ServletContext.getResourceAsStream()
> 
> The problem is the following sequence:
> - request for JSP
>   - no change in JSP timestamp found
>   - cache re-validated (for 5s by default)
> - JSP is modified (within 5s)
> - request for JSP (within 5s)
>   - change in JSP timestamp found
>   - JSP content read (sees cached version rather than new version)
> 
> So we end up with the old version of the JSP content with the updated
> last modification time.
> 
> I'm currently looking at options to return a URL for the resource where
> we can intercept the call to URLConnection.getLastModified().

Fixed in:
- master for 9.0.28 onwards
- 8.5.x for 8.5.48 onwards

Mark

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