100% CPU nginx master process

[badtzhou]

We are have issue that nginx master process is at 100% CPU and it stop
responding to any request. The CPU utilization for all the workers are low.

I am also seeing multiple nginx master process running at the same time when
server stop responding, all of them are at 100% CPU. For my understand,
there should only be one master process. What will cause multiple master
process running?

The problem is very intermittent. It will go away by itself.

Any kind of help will be appreciated.

Thanks

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,248029,248029#msg-248029