我有生产服务器(Nginx Passenger).当我尝试从另一台计算机ab -n 3 -c 3 myhost.ru/时,我在我的nginx error.log中收到此错误日志：

[ pid=21160 thr=139775297914624 file=ext/nginx/HelperAgent.cpp:584 time=2011-08-31 15:25:49.22 ]: Uncaught exception in PassengerServer client thread:
   exception: Cannot read response from backend process: Connection reset by peer (104)
   backtrace:
     in 'void Client::forwardResponse(Passenger::SessionPtr&,Passenger::FileDescriptor&,const Passenger::AnalyticsLogPtr&)' (HelperAgent.cpp:330)
     in 'void Client::handleRequest(Passenger::FileDescriptor&)' (HelperAgent.cpp:510)
     in 'void Client::threadMain()' (HelperAgent.cpp:603)

[ pid=21249 thr=15884760 file=utils.rb:176 time=2011-08-31 15:25:49.022 ]: *** Exception PGError in application (server closed the connection unexpectedly
  This probably means the server terminated abnormally
  before or while processing the request.
) (process 21249,thread #