KmlOverlayService 500 Internal Server Error

[Matthew C]

I'm intermittently getting a 500 Internal Server Error when I try to load one specific KML layer on my maps API implementation, development version at http://foothill-web-gis.googlecode.com/svn/trunk/webgis/fhwebmapdemo.html. Here's the error (as reported by Firebug; I've also seen it in Chrome 11, and my colleague has seen it in Firefox 3.6 on Windows 7):

GET http://maps.googleapis.com/maps/api/js/KmlOverlayService.GetOverlays?1shttp%3A%2F%2Ffoothill-web-gis.googlecode.com%2Fsvn%2Fdata%2Frooms1.kml%3Frandom%3D0.45035833644684664&callback=_xdc_._5r6577&token=39032
500 Internal Server Error

Response Headers

Date	Mon, 30 May 2011 04:04:02 GMT
Content-Type	text/html; charset=UTF-8
Server	mafe
Content-Length	11957
X-XSS-Protection	1; mode=block

Request Headersview source

Host	maps.googleapis.com
User-Agent	Mozilla/5.0 (X11; Linux i686; rv:2.0) Gecko/20100101 Firefox/4.0
Accept	*/*
Accept-Language	en-us,en;q=0.5
Accept-Encoding	gzip, deflate
Accept-Charset	ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive	115
Connection	keep-alive
Referer	http://foothill-web-gis.googlecode.com/svn/trunk/webgis/fhwebmapdemo.html

Cache information:

Last Modified	Sun May 29 2011 21:04:02 GMT-0700 (PDT)
Last Fetched	Sun May 29 2011 21:04:02 GMT-0700 (PDT)
Expires	Wed Dec 31 1969 16:00:00 GMT-0800 (PST)
Data Size	11957
Fetch Count	2
Device	disk

Opening the above URL directly gives Google's standard error page.

Here's the KML file in question: http://foothill-web-gis.googlecode.com/svn/data/rooms1.kml

It's large (~1.2MB), but under Google's 3MB limit, and has a lot of features (877, but under Google's limit of 1000), so I'm not exactly sure what's going on. I'm serving out of the project SVN and I've forced caching on the KML off (since I'm updating it frequently right now), and some have suggested that it's just the SVN server being slow and Google giving up fetching it, but I'm not sure if that's correct. I've speedtested the download, and I'm getting 93-128K down when the map is failing (which is pretty near the limits of my 'net connection). Switching to a KMZ seems to help, but I'd like to know what's going on here so I can avoid it.

Has anyone seen this problem or have any insight? Thanks in advance!
-Matt

[Matthew C]

By the way, http://code.google.com/apis/maps/documentation/javascript/forum.html?place=forum/google-maps-js-api-v3 seems to be related, but they're discussing dynamically generated KML and this is static and there doesn't seem to be an answer there either. Meant to mention this thread in the original post, sorry about that.
-Matt

[James McGill]

Hi Matt,

You are correct in inferring that the file is taking too long to fetch.

By appending a random number (to prevent Google caching the file) you
are effectively making the KML file dynamic - Google must download and
parse the file every time you change that random number.

I used wget to time downloading that file a few times, and saw a
median download time of 6 seconds and a maximum of 59 seconds (SVN is
probably not well suited to acting as a content server). Ideal
download times would be under 1 second.

Some suggestions:
* Most importantly, do not append random numbers to your KML file when
your site is in production. Change the URL only when the content of
the underlying KML file has actually changed. During development is
fine.

* Consider zipping the file and serving it as a *.kmz file. It
compresses from 1.2M to 124K which should download much faster.

* Serve the file from a faster or more consistent server. I've found
that Google AppEngine works well for static files.

Regards,
James

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[James McGill]

For those interested, here's the command I used to time downloads:

time wget -S http://foothill-web-gis.googlecode.com/svn/data/rooms1.kml?randomnumberhere

Looking at the download speed is insufficient as it doesn't take into
account the size of the file, or request latency.

Regards,
James

[Matthew C]

OK, thanks for shedding some light on the matter. I plan to switch to KMZ, and I certainly won't be serving from SVN in production! The random numbers, too, will disappear in production.

[Matthew C]

Closing topic.