Hi Andrea,
Are you talking about serving cached tiles or tiles that need to be built
on the fly?
Both. I pre-seed some area to a certain zoom level, but I'm also leaving
most of the seeding to be done by users on the fly.
Yes, this is well known, see this proposal I made at the beginning of 2017,
it contains some performance numbers too:
https://github.com/geoserver/geoserver/wiki/GSIP-155
I cannot tell you how much of those 80ms are weighting on WMTS calls
hitting already cached tiles on the embedded GWC, but I'm confident part of
it will be there.
I didn't quite look at it this way. But actually the JDBCConfig is a big
difference between my clustered environment and the Single Geoserver. I
could be going after GWC but the quesries are most likely the issue.
However, this si a sacrifice I have to make to share the catalog between
different machines.
Kind regards,
Steve Omondi
On Tue, Nov 7, 2017 at 9:07 PM, Andrea Aime <andrea.a...@geo-solutions.it>
wrote:
> On Tue, Nov 7, 2017 at 3:05 PM, Steve Omondi <steve.omo...@ramani.co.ke>
> wrote:
>
>> I have 6 Geoservers + Embedded GWC spread on two VMs 3 each. Each
>> running on separate Tomcat. All the Six Geoserver are running behind Apache
>> HTTPD proxy Balancer. I tried tuning the Java Process setting to optimum.
>>
>> On the other hand I had a single Geoserver+ Embedded GWC.
>>
>> On performing tests, The 6 Geoserver are 4-6 time slower than the Single
>> Geoserver while rendering a layergroup of HR Aerial Imagery on Openlayers
>> client.
>>
>> I made a list of the configuration differences between the clustered
>> Geoservers and the Single Geoserver and some of the items are;
>>
>> - I use Authkey for Authentication in the Clustered Geoservers with a
>> JDBC Role Service - so maybe every tile request has to perform
>> authorization by querying the database and all those processes may slow
>> the
>> request.
>>
>>
> This certainly adds work, queries to databases are expensive (how much so,
> depends a lot on your configuration, network, indexes and the like)
>
>>
>> - JDBCConfig is used in the clustered Geoserver as opposed to XML
>> Catalog in the Single Geoserver; same as above the query process could be
>> slowing requests.
>>
>> Yes, this is well known, see this proposal I made at the beginning of
> 2017, it contains some performance numbers too:
> https://github.com/geoserver/geoserver/wiki/GSIP-155
> I cannot tell you how much of those 80ms are weighting on WMTS calls
> hitting already cached tiles on the embedded GWC, but I'm confident part of
> it will be there.
>
>
>>
>> - The fact that *GWC Directory and Diskquota are clustered could be
>> an issues*; write/access speed of the remote GWC directory seems to
>> me as a cause of slow rendering of tiles and as so it tops my list of
>> culprits.
>>
>> That depends a lot on the network file system in use.
>
>
>> The third point is the source of my motivation to run GWC as standalone
>> in front of the Geoserver Cluster proxy. The have the GWC Blobstore closer
>> instead of a network drive.
>>
>> Can you elaborate what you mean by "as efficient
>> and fast"?
>>
>> My experience with the Integrated GWC (Six Instances of them which do not
>> share workload) is definitely slower as I've mentioned 4 -6 times slower
>> that a single GWC.
>>
>
> Are you talking about serving cached tiles or tiles that need to be built
> on the fly?
>
>
>>
>> In fact I have stopped one VM and move the Tiles (GWC dir) to a local
>> directory in the same machine as the Geoservers but still slower than one
>> Geoserver.
>>
>
> Yeah, the two common topologies are:
>
> - Shared network storage, mostly read only, pre-seeded on some other,
> non online machine
> - One tile storage per network node, non shared, especially useful for
> data changes a lot
>
> I'd love to see a local storage option that allows picking tiles from
> other nodes via some clustering technology (e.g., hazelcast distribution),
> merging the benefits of the two world but... it's missing funding to be
> developed
>
> Cheers
> Andrea
>
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