On Mon, Dec 12, 2016 at 1:58 PM, Niels Charlier <ni...@scitus.be> wrote:
> I have another question though - why is geoserver doing this thing in
> GeoServerInitStartupListener? I'm not just asking about the place it is
> doing, why is it doing this at all? What was the original idea behind it
> and does it still count? I think ImageWorker is on the classpath of
> geoserver in any case, so whether it does its own JAI initialisation before
> or after ImageWorker, it seems pointless. Or am I wrong?
>
For most things I believe there is no obvious/simple alternative to
performing certain inits as the very first action while the app starts up.
Let's have a look line by line:
- GeoTools initialization, that needs to be done very first thing to
avoid losing logging and JAI logs, https://github.com/
geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/
GeoserverInitStartupListener.java#L85
<https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/GeoserverInitStartupListener.java#L85>
- Avoid logs on standard error in JAI, also needs to be done first, or
we might get some spurious logs during system init, https://github.com/
geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/
GeoserverInitStartupListener.java#L88
<https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/GeoserverInitStartupListener.java#L88>
- Setting up JAI alternative registry and tile cache, yep, also needs to
be done very first thing, if not you already know what the consequences
are: https://github.com/geoserver/geoserver/blob/
master/src/main/src/main/java/org/geoserver/GeoserverInitStartupListener.
java#L121
<https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/GeoserverInitStartupListener.java#L121>
Not setting up these two at all will have dire scalability and runtime
consequences, either under high load or in certain conditions (e.g., highly
oversampled requests)
- Forcing axis order, also needs to be done before anything starts using
the CRS factories or the order won't be the expected one,
https://github.com/geoserver/geoserver/blob/
master/src/main/src/main/java/org/geoserver/GeoserverInitStartupListener.
java#L141
<https://github.com/geoserver/geoserver/blob/master/src/main/src/main/java/org/geoserver/GeoserverInitStartupListener.java#L141>
This could actually be avoided by applying everywhere the same changes
you just proposed in the geopackage module, and that would be applied in
several other places as well, plus changing the axis order logic in WMS
1.3, in WFS, in the GML encoder, and so on... doable, not sure anyone is
willing to spend days to chase all the points where this happens, and then
discoverer 6 months later that a few have been missed (not to mention, the
effect on plugins that are not in the GeoTools/GeoServer source trees,
those would have to be updated too).
Anyways, worth pursuing imho, just hard to fund.
- The rest of the inits in that method are also needed to be done very
first thing, but are a bit less obvious to explain. Suffice it to say that
not doing those will have other adverse effects, either functional,
performance or availability related
The JAI initializations should not be moved to the ImageWorker for the
simple reason that not everything uses the ImageWorker, and its
initializations are specific to a few operations... if anything, I'd move
the ImageWorker inits somewhere else instead. However there is no obvious
place at the moment, GeoTools.init would not have the necessary classes in
the classpath.
_Maybe_ a plugin system could be developed to allow per module inits that
would be called as GeoTools.init is called.... still, people would have to
remember to call it.
Not all use cases will need all the inits that GeoServer is performing, a
desktop application will likely not need several of them (several of the
JAI related ones) and under different conditions, different registries and
tile caches (we have done several times in GeoSolutions to adapt to the
specific environment requirements).
Cheers
Andrea
--
==
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==
Ing. Andrea Aime
@geowolf
Technical Lead
GeoSolutions S.A.S.
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