On Thu, May 23, 2013 at 5:48 AM, Ben Caradoc-Davies <
ben.caradoc-dav...@csiro.au> wrote:
> Mauro,
>
> your improvements to SchemaCache have also introduced an unanticipated
> problem triggered by download failure:
> https://jira.codehaus.org/browse/GEOT-4467
>
> You set a 10 second timeout on connections and reads. It turns out that
> some application schemas, including that used in the GeoServer
> app-schema tutorial, import this W3 schema, which often takes more than
> 10 seconds to connect:
> http://www.w3.org/2001/xml.xsd
Ah, this one is a nightmare, it's always super-slow to download (I guess
because
anything XML ends up linking it).
Imho, we should have a copy of it baked directly into code to avoid
downloading it
over and over.
> (1) Why do you set a timeout at all? Just a best practice to avoid an
> application hang? (Good idea!) If so, the obvious workaround is to
> increase the timeout (60 seconds?) to accommodate slow servers. Would
> this be a satisfactory solution?
>
I'd say, make it configurable. 10 seconds to start responding in 2013 is
not slow,
it's a geologic era...
>
> (2) Please look at the logic in SchemaCache.startDownload(). Why is it
> necessary to create an empty file? How should SchemaCache recover when a
> download fails? Please have a look and recommend a solution. I know you
> gave this some thought and I do not want to introduce a deadlock or
> thread blocking that might impact your performance.
>
Fully agree this is a problem
>
> The original AppSchemaCache had no timeout and did not write to a file
> until it had all the bytes of the remote resource, so 9.x is not
> affected by these issues.
>
Right right, good idea to complete the write on disk only when the download
is complete to avoid half downloaded files. But keeping everything in memory
could be dangerous, maybe write a temp file and rename it to the final
destination once done
Cheers
Andrea
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