Q: What is the information after the PID in the nginx error log? I'm trying to parse my nginx error logs into structured data, but I can't quite figure out what information is being conveyed by the part of text that's attached to the PID. For example, I have an error line like this:
2014/06/05 15:15:44 [error] 19194#0: *1308 upstream timed out (110: Connection timed out) while reading response header from upstream, client: XXX.XXX.XXX.XXX, server: beta.site.com, request: "POST /api/v1/products.json HTTP/1.1", upstream: "fastcgi://unix:/var/run/php-fpm/php-fpm.sock", host: "beta.site.com"

The PID section looks like 19194#0. 19194 is the PID, but I can't figure out what #0 means. Any ideas?

A: I think I've got the answer. It seems to be the line number of the message in the error log. So for single line messages it will put a "#0". But any subsequent lines for the same message will have a "#1" or "#2", without the pid (or other message prefix like timestamp).
