Possible memory leak?

[Anoop Alias]

I am able to reproduce the issue @wkbrad is reporting

[root at server1 ~]# ps_mem|head -1 && ps_mem|grep nginx
 Private  +   Shared  =  RAM used       Program
 25.3 MiB + 119.5 MiB = 144.9 MiB       nginx (3)
[root at server1 ~]# systemctl restart nginx
[root at server1 ~]# ps_mem|head -1 && ps_mem|grep nginx
 Private  +   Shared  =  RAM used       Program
 24.2 MiB +  58.1 MiB =  82.2 MiB       nginx (4)
 -------------------------->  notice the sharedmemory usage is half os what
is used before restart
[root at server1 ~]# ps_mem|head -1 && ps_mem|grep nginx
 Private  +   Shared  =  RAM used       Program
 23.1 MiB +  57.9 MiB =  81.0 MiB       nginx (3)
 ---------------------------> the cache loader process exits and the ram
usage remain same
[root at server1 ~]# nginx -s reload
   ---------------------------> A graceful reload is performed on Nginx
[root at server1 ~]# ps_mem|head -1 && ps_mem|grep nginx
 Private  +   Shared  =  RAM used       Program
 15.8 MiB + 118.8 MiB = 134.5 MiB       nginx (3)
 ----------------------------> The shared RAM size doubles and stay at this
value till another restart is performed



##############################################################################

I think this is because the pmap shows 2 heaps after reload whereas there
is only one right after the restart , An additional heap appears after
reload

[root at server1 ~]# systemctl restart nginx
[root at server1 ~]# ps aux|grep nginx
root     22392  0.0  0.7 510316 62184 ?        Ss   13:49   0:00 nginx:
master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
[root at server1 ~]# pmap -X 22392|head -2 && pmap -X 22392|grep heap
22392:   nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
         Address Perm   Offset Device      Inode   Size   Rss   Pss
Referenced Anonymous Swap Locked Mapping
        01b10000 rw-p 00000000  00:00          0  61224 58688 17187
 80     58688    0      0 [heap]


Now after the reload


[root at server1 ~]# pmap -X 20983|head -2 && pmap -X 20983|grep heap
20983:   nginx: master process /usr/sbin/nginx -c /etc/nginx/nginx.conf
         Address Perm   Offset Device      Inode   Size    Rss   Pss
Referenced Anonymous Swap Locked Mapping
        02780000 rw-p 00000000  00:00          0  61224  61220 23118
51540     61220    0      0 [heap]
        0634a000 rw-p 00000000  00:00          0  57856  55360 19138
55360     55360    0      0 [heap]
###########################################################################


On Tue, Mar 12, 2019 at 2:07 AM wkbrad <nginx-forum at forum.nginx.org> wrote:

> Hi All,
>
> I think I haven't been clear in what I'm seeing so let's start over.  :)  I
> set up a very simple test on Centos 7 with a default install of Nginx
> 1.12.2.  Below is exactly what I did to produce the result and it's clear
> to
> me that Nginx is using 2x the ram than it should be using after the first
> reload.  Can anyone explain why the ram usage would double after doing a
> config reload?
>
> yum update
> reboot
> yum install epel-release
> yum install nginx
> systemctl enable nginx
> systemctl start nginx
> yum install ps_mem vim
> cd /etc/nginx/
> vim vhost.template
>
> --------------------------------------------------------------------------------
> server {
> listen 80;
> listen [::]:80;
>
> server_name {{DOMAIN}};
>
> root /var/www/html;
> index index.html;
>
> location / {
> try_files $uri $uri/ =404;
> }
> }
>
> --------------------------------------------------------------------------------
> cd conf.d
> for i in $(seq -w 1 50000); do sed 's/{{DOMAIN}}/dom'${i}'.com/'
> ../vhost.template > dom${i}.conf; done
> systemctl restart nginx
> ps_mem|grep nginx
>
> --------------------------------------------------------------------------------
>  13.8 MiB + 750.7 MiB = 764.5 MiB       nginx (3)
>
> --------------------------------------------------------------------------------
> systemctl reload nginx; sleep 60; ps_mem |grep nginx
>
> --------------------------------------------------------------------------------
>  27.2 MiB +   1.4 GiB =   1.5 GiB       nginx (3)
>
> Posted at Nginx Forum:
> https://forum.nginx.org/read.php?2,283216,283344#msg-283344
>
> _______________________________________________
> nginx mailing list
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> http://mailman.nginx.org/mailman/listinfo/nginx
>


-- 
*Anoop P Alias*
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