Threaded bind on CentOS

Jack Tavares j.tavares at
Thu Feb 24 22:31:32 UTC 2011

> -----Original Message-----
> From: Chris Thompson [mailto:cet1 at] On Behalf Of Chris
> Thompson
> Sent: Thursday, February 24, 2011 1:21 PM
> To: Jack Tavares
> Cc: bind-users at
> Subject: Re: Threaded bind on CentOS
> On Feb 24 2011, Jack Tavares wrote:
> >I am using bind 9.7.3 and I have tried running it with
> >various -n values and it appears that I will always get
> >n+3 threads.
> >
> >Ex:
> >I run it:
> >
> >named -n 1
> >I get 4 threads
> >named -n 4
> >I get 7 threads
> >
> >etc.
> >
> >I understand the desire to have background "housekeeping"
> >threads, but I would like to know what, exactly, those threads do.
> This is standard in any threaded BIND - it isn't specific to your OS.
> There are $N worker threads and 3 overhead/management ones. I wouldn't
> mind a description of the latter from ISC myself ...

I mentioned the CentOS because some folks will automatically ask
if the info isn't included.

And someone replied off list with this:
Yes. The FAQ at the apex of the source tree:

Q: Why do I see 5 (or more) copies of named on Linux?

A: Linux threads each show up as a process under ps. The approximate
    number of threads running is n+4, where n is the number of CPUs.  
    that the amount of memory used is not cumulative; if each process is
    using 10M of memory, only a total of 10M is used.

    Newer versions of Linux's ps command hide the individual threads and
    require -L to display them.
end quote:

I grep-ed through the doc/ directory and below and didn't find anything.
I didn't think to check the FAQ.

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