cpu spike on HUP

Gary Barrueto gary at justin.tv
Fri Oct 29 03:55:40 MSD 2010

Whenever nginx is sent a HUP signal, the cpu jumps to 100% then slowly 
drops until all the nginx worker processes that are trying to shutting 
down are done. Those nginx process usually take a while to shutdown 
since we're serving very large files (200MB-2GB). Any ideas why this is 

 From the strace below it looks like it all in sendfile but I wouldn't 
think that would so cpu intense.


/usr/local/nginx/sbin/nginx -V
nginx version: nginx/0.8.52
built by gcc 4.4.3 (Ubuntu 4.4.3-4ubuntu5)
TLS SNI support enabled
configure arguments: --with-http_ssl_module --with-http_flv_module

This is from about 10 seconds of strace of one of the nginx process 
while shutting down.

sudo strace -cp 7087
Process 7087 attached - interrupt to quit
^CProcess 7087 detached
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
  99.85    0.071681         139       515           sendfile
   0.15    0.000110           0       252           epoll_wait
------ ----------- ----------- --------- --------- ----------------
100.00    0.071791                   767           total

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