Troubleshooting a high-load scenario

Matthias Lang <>
Tue Jan 17 14:28:17 CET 2006


Joel Reymont writes:

 > It appears that the bots cannot cope with such an influx of messages
 > but I would like to be sure that the issue is indeed in my harness
 > and not in the poker server.

Are you working to understand the system, or just twiddling random
knobs in public in the hope of sudden "problem disappearance"?

I'd _start_ with this experiment

  1. Find a value N such that

         a) a load generator running N bots runs acceptably

     AND b) a load generator running M bots, where N < M < 2N,
            does not run acceptably.

  2. Use two load generators (i.e. seperate, otherwise idle
     machines!), each running N bots.

The system's behaviour in those two runs will most likely give you a
strong indication of where the bottleneck is. But random twiddling is
less ambitious and more amusing, especially for the audience.

Next step: sniff the network and analyse the traffic.

Matthias

N.B. Your description of the problem leaves open the possibility of
the number of messages being quadratically related to the number of
subscribers. My experiment above is set up for a linear relation.



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