Safe log rotation

[jmobile]

Hi,

I'd like to check how nginx handles command from
http://wiki.nginx.org/LogRotation
kill -USR1 `cat /var/run/nginx.pid`

I'm using it to recreate log files during rotation.

My question if any loglines can be lost in case time interval between
physical log files rotation and USR1 is large enough, like seconds? Or if
load is very high. 

For example, while I was sending traffic to website with "ab -n 20 -c 10
http://test-s.mysite.com/static/99$i/logo/test.png > /dev/null 2>&1" in the
loop, I executed on the web-server this

tail -n 5 /mnt/vg0-lv0/access.log 
rm -rf /mnt/vg0-lv0/access.log
sleep 15; sudo kill -USR1 `cat /var/run/nginx.pid` 
sleep 2
head -n 5 /mnt/vg0-lv0/dj-access.log

2014-10-01T21:16:10+00:00,1412198170.957,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2486547,1,201,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:10+00:00,1412198170.957,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2486548,1,240,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:10+00:00,1412198170.958,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2486549,1,279,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:10+00:00,1412198170.959,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2486550,1,318,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:10+00:00,1412198170.964,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2486551,1,279,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"

...

2014-10-01T21:16:27+00:00,1412198187.024,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2489854,1,162,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:27+00:00,1412198187.024,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2489855,1,162,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:27+00:00,1412198187.024,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2489856,1,162,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:27+00:00,1412198187.024,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2489857,1,240,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"
2014-10-01T21:16:27+00:00,1412198187.024,10.120.71.11,"-","206.223.189.242",test-s.mysite.com,2489858,1,279,"-","-","-",-,"-","-","ApacheBench/2.3","-",HTTP/1.0,GET,http,/static/logo/test.png,"-",200,5676,5150,0.000,"-","-"

As you can see, there is a gap in timestamps sequence. 
Is there a way to make sure all log-lines are going to be written on a
highly loaded web farm?

Thank you,
Roman Naumenko

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,253681,253681#msg-253681