thundering herd problem

thundering herd problem


   Scheduler thrashing. This can happen under Unix when you have a number
   of processes that are waiting on a single event. When that event (a
   connection to the web server, say) happens, every process which could
   possibly handle the event is awakened. In the end, only one of those
   processes will actually be able to do the work, but, in the meantime,
   all the others wake up and contend for CPU time before being put back
   to sleep. Thus the system thrashes briefly while a herd of processes
   thunders through. If this starts to happen many times per second, the
   performance impact can be significant.