Cpu spike on HUP

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
happening?

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

-gary

/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

On Thu, Oct 28, 2010 at 04:55:40PM -0700, Gary Barrueto wrote:

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
happening?

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

What kind of CPU is used in these moments: system or user according to
top ?

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


Igor S.
http://sysoev.ru/en/

On 10/29/2010 01:02 AM, Igor S. wrote:

What kind of CPU is used in these moments: system or user according to top ?

I just sent a HUP signal to nginx and the cpu shot up to 55% user and
another 10% sys.

-gary

On Fri, Oct 29, 2010 at 02:02:29PM -0700, Gary Barrueto wrote:

think that would so cpu intense.
What kind of CPU is used in these moments: system or user according to top ?

I just sent a HUP signal to nginx and the cpu shot up to 55% user and
another 10% sys.

Do you send a HUP signal to master process only or to worker processes
too ?


Igor S.
http://sysoev.ru/en/

On 10/30/2010 2:13 AM, Gary Barrueto wrote:

On 10/29/2010 11:07 PM, Igor S. wrote:

I just sent a HUP signal to nginx and the cpu shot up to 55% user and
another 10% sys.
Do you send a HUP signal to master process only or to worker
processes too ?
I sent the HUP signal to the master process.
-gary

Normally, the cpu is at 1% user and system is at 2% when serving
60-90MB/sec.

-gary

On 10/29/2010 11:07 PM, Igor S. wrote:

I just sent a HUP signal to nginx and the cpu shot up to 55% user and
another 10% sys.
Do you send a HUP signal to master process only or to worker processes too ?

I sent the HUP signal to the master process.

-gary

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