I have moved my prototype implementation of a timeout format option into
GeoServer as part of the RenderedImageMapOutputFormat. (Pull Request here:
https://github.com/geoserver/geoserver/pull/1055 ).
Changes:
- Added a "timeout" format option to the RenderedImageMapOutputFormat.
Allows users to specify a timeout in ms. The renderer will use the nonzero
minimum of this timout and the WMS global timeout.
- Moved the actual rendering out to a seperate thread. This means that
if we reach the timeout, we can return immedialtly, and let GeoServer clean
up the renderer on its own time, rather than waiting for the current
request to finish.
There is one bit of code that I am a bit leery of adding. The clean up
process for the renderer will forcibly terminate the thread (Thread.stop())
if it does not end itself after 1000 ms of being asked to. This helps keep
geoserver running quickly after timing out a large request, but leads to
its own complications. I feel like there are two options here:
- Keep as-is. Means we are using Thread.stop(), which may result in
memory leaks, headless exceptions, etc.
- Allow the renderer to stop itself, even if it takes a while. If
geoserver gets a large number of massive requests, could lead to all
resources being used waiting for the renderers to clean up after themselves.
I am currently getting two test failures that I cannot explain:
Failed tests:
testParameterizedStyle(org.geoserver.wms.featureinfo.GetFeatureInfoJSONTest):
expected:<[1]> but was:<[0]>
testParameterizedStyle(org.geoserver.wms.wms_1_1_1.GetFeatureInfoTest):
expected:<[1]> but was:<[0]>
My change does not touch anything related to getFeatureInfo or styles, yet
these tests fail on my branch but pass on master. Any ideas?
I am also currently looking into adding an exceptions format that allows
returning of a partial image if a GetMap fails during timeout.
Feedback is welcome.
Torben
On Fri, Apr 17, 2015 at 9:15 AM, Torben Barsballe <
[email protected]> wrote:
> Yes, the code I am writing uses the minimum of the two, as long as both
> are nonzero.
>
> Torben
>
> On Fri, Apr 17, 2015 at 9:12 AM, Andrea Aime <[email protected]
> > wrote:
>
>> On Fri, Apr 17, 2015 at 6:05 PM, Torben Barsballe <
>> [email protected]> wrote:
>>
>>> Hello,
>>>
>>> I propose to add a format parameter (format_options=timeout:<timeout>)
>>> to the WMS RenderedImageMapOutputFormat that allows users to specify a
>>> timeout on individual requests (As opposed to the global WMS configuration
>>> *maxRenderingTime
>>> *option.
>>>
>>> In conjunction with this, I would like to add an exceptions
>>> <http://docs.geoserver.org/stable/en/user/services/wms/reference.html#exceptions>
>>> option to return a partial image if rendering is interrupted.
>>>
>>> I have prototyped some of this functionality locally, and it seems
>>> viable.
>>>
>>
>> Sounds like an interesting improvement, provided the code uses the lowest
>> between the globally configured limit and the user provided one.
>> Allowing users to go beyond the admin configured limit is just going to
>> make it too easy to mount a DOS attack on the cheap.
>>
>> Cheers
>> Andrea
>>
>> --
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>> Ing. Andrea Aime
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