[mapguide-users] Best Performance for about 100 Unique Users

[Jackie Ng]

Let me shed you some insight on scalability based on some automated stress
testing I've done with the 2.4 beta

The SessionRepositoriesLimit configuration property determines the maximum
amount of sessions. Each CreateSession call will create a new session repo
file up to the specified limit in serverconfig.ini. Once that limit is
breached, the MapGuide Server will throw
MgRepositoryCreationFailedExceptions on any future CreateSession calls.

So how does this number go down? That's where session expiry comes in. For
any sessions that are expired, the MapGuide Server will delete the matching
repository, bringing down the number of active session repositories.

See where this is going? You have to tune your session expiry settings (ie.
lower them) to ensure sessions will expire at the rate that sessions are
created to ensure the SessionRepositoriesLimit isn't breached.

In a way it's analogous to memory management. CreateSession is allocating
memory. MapGuide's session expiry is effectively your garbage collector. If
the garbage collector isn't aggressive enough, you'll eventually be out of
memory (SessionRepositoriesLimit is reached) because memory allocations are
outpacing the garbage collection. And actually that analogy is rooted in
some fact as actual memory use by the MapGuide Server has correlation to the
active number of sessions. More active sessions = More memory used. As
MapGuide cleans up expired sessions, the memory use falls in step.

For the record, my stress test (started 50 mins ago, still running as I
write this) is:

50 simulated users on the Sheboygan dataset

serverconfig.ini modified:

SessionRepositoriesLimit = 2000
SessionTimerInterval = 60
SessionTimeout = 200

My hardware is a Quad Core Windows 7 desktop w/ 8 GB ram.

Under these stress test parameters, MapGuide memory usage plateaus at 3gb
and active session repository files plateaus at around 1400-1500 and then
stays there. No errors have been logged yet. 

You could extrapolate these numbers to fit your particular scenario.

- Jackie

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