[mapserver-users] Mapserver/PostGIS Faster Initial Load Time

[Lime, Steve D (DNR)]

I've noticed latency the first time mapserv is executed, presumably as a result of loading into memory and dynamic linking. Once the OS caches everything it's nice and snappy. I tend to see that only on my development versions though because on our production boxes the executables are hit often enough that they are always in memory. Unless access is very infrequent I'd think latency due to loading a binary would be rare. 

I suppose you could simulate traffic on the server-side to make sure everything is memory resident. That is, make a small request every 5 minutes or whatever using cron or the Windows equivalent.

I'm not experienced enough with PostGIS to know if there's any tuning to do there. Maybe others have ideas.

Steve

________________________________________
From: Donald Kerr [donald.kerr at dkerr.co.uk]
Sent: Friday, June 08, 2012 9:16 AM
To: Lime, Steve D (DNR); 'mapserver-users'
Subject: RE: [mapserver-users] Mapserver/PostGIS Faster Initial Load Time

Steve,

It's not a scientific measurement. For this particular example, the whole
setup (server and client) is on a XP SP3 machine with 4 Gb memory. From the
point when the mapping page is requested, the time taken to start seeing
tiles returned is about 15 seconds. After that initial time, the images come
in thick and fast. I'm pretty sure that it's the first load of mapserv.exe
and, if the requested layer is via postgis, the first load of postgis. I'm
trying to think of ways to speed up that initial load like, as I said in the
last post, requesting a map tile on the fly (and hidden) so that mapserv.exe
has been run once and is in memory ready for the next, or first 'real',
request. It's probably the only downside to a system that I've got running
like a little sweetie just now.

It's basically a classic asp website running on IIS but I can switch between
IIS and Apache for the mapping WMS/WFS. Both are quite fast and both run
FastCGI though Apache seems a little more stable when a lot of tiles are
requested with a lot of fast map drags; sometimes IIS gives up on individual
request. Whether IIS or Apache, there's still this initial load delay of
about 15 seconds. This may be something that I have to live with but I'm
trying to improve that initial load if possible.

To go back to your original question, my guess is that the load time is a
server issue rather than a client problem though I may be wrong.

Regards,

Donald

-----Original Message-----
From: Lime, Steve D (DNR) [mailto:Steve.Lime at state.mn.us]
Sent: 08 June 2012 15:03
To: Donald Kerr; 'mapserver-users'
Subject: RE: [mapserver-users] Mapserver/PostGIS Faster Initial Load Time


Where/how are you measuring times (server/client)?

________________________________________
From: mapserver-users-bounces at lists.osgeo.org
[mapserver-users-bounces at lists.osgeo.org] on behalf of Donald Kerr
[donald.kerr at dkerr.co.uk]
Sent: Wednesday, June 06, 2012 2:35 PM
To: 'mapserver-users'
Subject: [mapserver-users] Mapserver/PostGIS Faster Initial Load Time

Basically my mapping setup is, from client to server, Openlayers WMS/WFS
(Internet Explorer on XP Pro SP3) - Mapserver CGI - Shapefile (Tiffs) or
PostGIS (XP Pro SP3 - IIS & FastCGI).

>From boot up, the initial, or first load of maps, takes up to 15 seconds.
After that, it flies along fine.

I've tried pre-loading in a hidden browser instance but that didn't work. I
cannot get that initial load time down at all.

Any tips to reduce the time taken for the first load of the software:
Specifically Mapserver whether it's creating the map from PostGIS or the
shapefile (Tiffs).

Many thanks.

Regards,

Donald

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