I get the follow error in the nginx log
[error] 17734#0: *6643 recv() failed (104: Connection reset by peer)
while reading response header from upstream, client: [cut],
server: [cut], request: "GET /venues HTTP/1.1", upstream:
"fastcgi://127.0.0.1:9000", host: "[cut]"
I have a dedicated box with 8 gb ram, quad core chip. Good server.
Nginx, php-fpm & mysql all latest versions running under ubuntu 10.04
I only get this when I stress test the server with siege. If I increase the number of concurrent connections to 100, I can get up to 20% of all requests to fail.
Furthermore, I don't get this on pages that have no mysql queries. And only a few failures on pages with moderate number of queries. Bit, I'm not sure if that's got to do anything with it.
I have a feeling this is something to do with php. But I can't figure it out.
Any suggestions of where to even start looking?
Update: and the php error log is silent. No record of anything going wrong
Best Answer
Most probably you ran out of php-fpm workers. The log was silent because nothing was wrong in the code itself - workers just were busy processing your requests. If you did not get this on pages without MySQL queries, the bottleneck was the MySQL DB. You should identify long-running queries (using
mytopor slow log feature or maybe some custom PHP logging around your SQL processing) and optimize them. Of course, "long queries" are actually quite short in high-load we world. Even 200ms query is long enough to put your server on its knees.