Howto kill and solve spawn-fcgi

I have tested spawn-fcgi and php fast cgi under heavy load

and sometimes nginx reports that is dead "Connection refused while connecting to upstream"

ab -c 200 -n 5000 http://localhost:8080/posts/

so i modified the /usr/bin/php-fastcgi startup script

PHP_FCGI_CHILDREN=10
PHP_FCGI_MAX_REQUESTS=1000
/usr/bin/spawn-fcgi  -C 10 -F 10 -a 127.0.0.1 -p 9000 -u www-data -f /usr/bin/php5-cgi