If you have a single search engine per physical machine, the number of processing threads per engine is dynamically determined for optimum performance, and should not require adjustment. If for some reason the number of CPUs changes, restart the engine to recalculate thread allocation.

If you are running multiple engines per machine, you may want to adjust the ratio of threads to engines for best performance. For example, if CPU utilization is always 100% and response times are slow, there may be too many threads.

The total number of threads across all engines should equal the number of processors. You can set this value in the maxSpareThreads property of the <ATG10dir>\Search10\SearchEngine\operating_system\bin\AESoapWaspConfig.xml file

maxSpareThreads = number_of_processors / number_of_engines

Using a lower total number of threads may result in limited CPU usage; a higher number, in increased response times. If you have adjusted the default settings to run multiple engines per machine and the number of CPUs changes, adjust maxSpareThreads accordingly.

You must restart the engines in order for changes to take effect.