Another option I am currently investigating for the static components of
my maps is tilecache (google it). That should at least take away some of
the load that mapserver rendering the image in memory will eat up.
Another option is to combine mapserver with fastcgi. There should be
documentation around.
Good luck, and indeed as Frank suggests, consider hiring an expert.
Frank will know one or more ;-)
Frank Warmerdam schreef:
Bruce Cheney wrote:
We have been given a requirement to support 5000 simultaneous
users. What we are finding is that MapServer bogs down around 400
simultaneous users on a test machine. It looks like it is likely
slowing because of the threading issue. We haven't tested on a
production machine but are estimating that it should support double
what are test machine could handle (double the processor and RAM).
So at least 800 simultaneous users. Divide that out with the 5000
and we need a minimum of 6-7 web servers supporting MapServer. We
will certainly scale this as is needed but I do need some idea going
in as to what is going to be required.
Bruce,
I'm curious how many map requests per minute you expect 800 simultaneous
users to generate.
Does this sound like results that others expect or is this quantity
above what others have tested? Also Does anyone know of a solution
in the works to run make mapserver thread safe and/or up the overall
speed? I am not complaining about the speed just wondering what is
in the works.
In various aspects MapServer is already thread safe though there are
also known "unsafe" components, and some components are wrapped by
big locks that significantly reduce the value of multiple threads.
Progress occurs by fits and starts, largely based on support from user
organizations depending on multi-threading. For instance, in 5.0 I
implement locking around OGR for a client of mine in Australia.
(This is a subtle way of suggesting you hire someone to make this
happen if it is what you want!)
All this aside, by default MapServer is *massively multi-threaded*.
I say this since the default operation is to start a new cgi instance
for each request - each is essentially an independent thread.
Of course, the downside of whole-process cgi style multithreading is
that very little context is preserved from request to request. Map
files, data file headers, etc all need to be reparsed for each request.
My point here is that you need to think carefully about the application
flow to take much advantage of multiple threading within a single
process.
Also, if I may channel Ed, if you wanted to squeeze more performance out
of mapserver, you really need to start by figuring out what it is
spending
it's time doing. Where is it spending it's time?
o waiting for disk? (perhaps you are reading more data than you need?)
o rendering (perhaps your data is overdense, or you are using expensive
rendering options?)
o parsing mapfiles (perhaps you mapfile has too many unused layers?)
etc.
Best regards,
--
Milo van der Linden
skype: milovanderlinden <skype:milovanderlinden?add>
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