why socket for communication between master and worker used the so large memory?

[MCoder]

it's description in man lsof

SIZE, SIZE/OFF, or OFFSET
    ... In other cases, files don't  have true  sizes  -  e.g., sockets,
FIFOs, pipes - so lsof displays for their sizes the content amounts it
finds in their kernel buffer descriptors (e.g., socket buffer size counts
or TCP/IP window sizes.) ...


2013/3/29 Maxim Dounin <mdounin at mdounin.ru>

> Hello!
>
> On Fri, Mar 29, 2013 at 06:04:54PM +0800, MCoder wrote:
>
> > my nginx is just a http tunul proxy http connection, and max connection
> is
> > just lower than 100.
> >
> > # ps aux
> > root     19849  0.0  0.0  18028  2452 ?        Ss    2012   0:00 nginx:
> > master process /usr/local/qqwebsrv/nginx/sbin/nginx
> > nobody   25389  0.1  0.0  19752  4104 ?        S    Mar25   9:07 nginx:
> > worker process
> > nobody   25390  0.1  0.0  19752  4104 ?        S    Mar25   9:03 nginx:
> > worker process
> > nobody   25391  0.1  0.0  19752  4108 ?        S    Mar25   8:46 nginx:
> > worker process
> > nobody   25392  0.1  0.0  19760  4116 ?        S    Mar25   8:58 nginx:
> > worker process
> >
> > # lsof | grep nginx | grep socket
> > nginx     19849       root    3w     unix 0xffff8102b7574380
> >  1677964948 socket
>
> [...]
>
> > nginx     25392     nobody    3u     unix 0xffff8102b7574380
> >  1677964948 socket
> > nginx     25392     nobody    6u     unix 0xffff8102dce9dcc0
> >  1677964950 socket
> > nginx     25392     nobody    8u     unix 0xffff81027785a980
> >  1677964954 socket
> > nginx     25392     nobody   12u     unix 0xffff81010e285100
> >  1677964958 socket
> >
> > # lsof |awk '$1=="nginx" && $NF == "socket" {n[$6]=$7} END {for (i in n)
> {m
> > += n[i]} print m / (1024 * 1024 * 1024)}'
> > 12.5018
>
> What makes you think that what you are counting is memory?  From
> here it looks like NODE column, with SIZE/OFF colum omitted for
> some reason (likely just empty).  On a linux system here the
> output looks like:
>
> $ lsof | egrep 'socket|SIZE'
> COMMAND     PID      USER   FD      TYPE             DEVICE SIZE/OFF
>  NODE NAME
> nginx     30299   mdounin    3u     unix 0xffff880224f836c0      0t0
> 1953927 socket
> nginx     30299   mdounin    6u     unix 0xffff880413ff0380      0t0
> 1953928 socket
> nginx     30300   mdounin    6u     unix 0xffff880413ff0380      0t0
> 1953928 socket
>
> --
> Maxim Dounin
> http://nginx.org/en/donation.html
>
> _______________________________________________
> nginx mailing list
> nginx at nginx.org
> http://mailman.nginx.org/mailman/listinfo/nginx
>
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