Nginx + PHP FASTCGI FAILS - how to debug ?

[Niro]

I have an Ubuntu 9.10 server on AMAZON EC2 running Nginx +PHP with PHP FASTCGI via port 9000.

The server runs fine for a few minutes and after a few minutes (several thousands of hits in this case) FastCGI dies and Nginx returns 502 Error.

Nginx log shows 2010/01/12 16:49:24  1093#0: *9965 connect() failed (111: Connection refused) while connecting to upstream, client: 79.180.27.241, server: localhost, request: "GET /data.php?data=7781 HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "site1.mysite.com", referrer: "http://www.othersite.com/subc.asp?t=10"

How can I debug what is causing FastCGI to die ?

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,40332,40332#msg-40332