100% CPU nginx master process

[Maxim Dounin]

Hello!

On Sun, Mar 02, 2014 at 05:40:09PM -0500, badtzhou wrote:

> 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?

Multiple master processes is not something expected to happen 
during normal operation.  Multiple master processes may be present 
during binary upgrade, but this isn't something expected to happen 
automatically.  It might also be new worker processes just spawn - 
before they were able to change name and credentials, I've seen 
something like this on systems with a LDAP-based user database 
used when LDAP server was unresponsive.

Note well that master processes doesn't handle client connections.  
Master process only manages worker processes and a configuration.  
If you see nginx not responding - there should be another reason 
for this.  Looking into nginx error log might be a good idea, as 
well as examining your system's logs.

-- 
Maxim Dounin
http://nginx.org/