Apache caught SIGTERM, shutting down and port 80 using by perl procceses

Question

Apache randomly shutdown and cant restart. Port 80 used by perl processes. When I kill processes which use port 80, apache can restart again.

log and results :

tail -50 /var/log/httpd/error_log

[Sat Jan 07 00:11:01 2012] [notice] caught SIGTERM, shutting down

ns1:/proc/15852# fuser -n tcp 80

80/tcp:               6072 15849 15852

ns1:/proc/15852# ls -l

total 0
-r-------- 1 apache apache 0 2012-01-07 00:30 auxv
-r--r--r-- 1 apache apache 0 2012-01-07 00:24 cmdline
-rw-r--r-- 1 apache apache 0 2012-01-07 00:30 coredump_filter
-r--r--r-- 1 apache apache 0 2012-01-07 00:30 cpuset
lrwxrwxrwx 1 apache apache 0 2012-01-07 00:37 cwd -> /var/www/html/phpMyAdmin-2.11.5-all-languages
-r-------- 1 apache apache 0 2012-01-07 00:24 environ
lrwxrwxrwx 1 apache apache 0 2012-01-07 00:37 exe -> /usr/bin/perl
dr-x------ 2 apache apache 0 2012-01-07 00:37 fd
-r--r--r-- 1 apache apache 0 2012-01-07 00:30 io
-r-------- 1 apache apache 0 2012-01-07 00:30 limits
-rw-r--r-- 1 apache apache 0 2012-01-07 00:30 loginuid
-r--r--r-- 1 apache apache 0 2012-01-07 00:37 maps
-rw------- 1 apache apache 0 2012-01-07 00:30 mem
-r--r--r-- 1 apache apache 0 2012-01-07 00:30 mounts
-r-------- 1 apache apache 0 2012-01-07 00:30 mountstats
-rw-r--r-- 1 apache apache 0 2012-01-07 00:30 oom_adj
-r--r--r-- 1 apache apache 0 2012-01-07 00:30 oom_score
lrwxrwxrwx 1 apache apache 0 2012-01-07 00:37 root -> /
-r--r--r-- 1 apache apache 0 2012-01-07 00:30 schedstat
-r-------- 1 apache apache 0 2012-01-07 00:30 smaps
-r--r--r-- 1 apache apache 0 2012-01-07 00:24 stat
-r--r--r-- 1 apache apache 0 2012-01-07 00:30 statm
-r--r--r-- 1 apache apache 0 2012-01-07 00:24 status
dr-xr-xr-x 3 apache apache 0 2012-01-07 00:30 task
-r--r--r-- 1 apache apache 0 2012-01-07 00:30 wchan

ns1:/proc/15852# /etc/init.d/httpd restart

Stopping httpd:
Starting httpd: Warning: DocumentRoot [/xxx/public_html] does not exist
Warning: DocumentRoot [/xxx/private_html] does not exist
[Sat Jan 07 00:48:37 2012] [warn] NameVirtualHost xx.xx.xx.xx:80 has no VirtualHosts
[Sat Jan 07 00:48:37 2012] [warn] NameVirtualHost xx.xx.xx.xx:443 has no VirtualHosts
(98)Address already in use: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
Unable to open logs

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Randomly, I mean, Uncertain time, some times in night when server has very low traffic. Sometimes has more traffic.

I don't know other process are taking port 80 or apache still usign port 80. If other process are taking port 80, I want to know which proceses and why they taking. And how can I avoid this.

In question there is a proc directory ls result of process (pid number 15852). This process using port 80. Maybe it will help to recognize problem.

In http error log there is only line about this problem:

[Sat Jan 07 00:11:01 2012] [notice] caught SIGTERM, shutting down

---- New edit, problem happend again. I try netstat command and in this case pid id 7574 ----

netstat -tpnl | grep ":80" result :

ns1:~# netstat -tpnl | grep ":80"
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 7574/apache3 -k sta 

ns1:/proc/7574# more cmdline
/usr/sbin/apache3 -k start
ns1:/proc/7574# ls /usr/sbin/apache3
ls: cannot access /usr/sbin/apache3: No such file or directory