I recently had to allow for a long running reporting task in a Rails app which is running under Passenger (mod_rails) on Nginx

The default setting is 60 seconds and setting send_timeout to 300 in the Nginx config wasn’t working.
After much searching, I found the answer. Edit

/ext/nginx/Conguration.c and change the lines:

ngx_conf_merge_msec_value(conf->upstream.send_timeout, prev->upstream.send_timeout, 60000);
ngx_conf_merge_msec_value(conf->upstream.read_timeout, prev->upstream.read_timeout, 60000);

to (for a 5 min timeout)

ngx_conf_merge_msec_value(conf->upstream.send_timeout, prev->upstream.send_timeout, 300000);
ngx_conf_merge_msec_value(conf->upstream.read_timeout, prev->upstream.read_timeout, 300000);

You will then need to recompile nginx and restart it (sending the HUP signal won’t work in this case)

Hope this helps someone else out there.