fastcgi restarts question

Luca De Marinis loop at
Tue Dec 22 14:35:30 MSK 2009


I have a setup where I need to restart my (rails) fastcgi processes rather
often (about hourly). I think the processes are being shutdown cleanly (ie:
a flag is set by a signal, and when the request completes they exit 0),
still, if the load is high nginx starts reporting error log lines like:

2009/12/21 18:42:20 [error] 25219#0: *277 upstream prematurely closed
connection while reading response header from upstream, client:, server:, request: "GET
/project/xeditor/visual_edit/1 HTTP/1.0", upstream:
"fastcgi://unix:/tmp/xmanager_fcgi.sock:", host: "dmzxmweb05:8080"

and starts spitting out 502 errors. The problem gets worse if more fastcgi
processes are started, but sometimes it does it even with 5 only (it's an 8
cpu box).

I cannot totally rule out the possibility that my processes are shutting
down less cleanly that they should (maybe a race condition?), but in testing
they seem to be shutting down ok, and so they should have finished sending
the response. Also, may this actually be caused by nginx "losing" connection
with the socket - receiving 0 bytes, rather than actually getting a partial

Is there some nginx config param I can tweak to try in order to get rid of
those 502's ?? or either any suggestion on somewhere else to look for
problems and solutions?


Luca de Marinis
Interact S.p.A.
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