mysql_connect very slow on vlan intermittently

[adrian murphy]

mysql 5.0.46-log
php 5.1.6

Hi I have a database server and a web server on a vlan.
Been getting reports that our site is intermittently very slow.
I did some apd profiling and found that every now and again a script that was
executing normally in well under a second was taking over 20 seconds.
On inspection it was mysql_connect that was sometimes very slow.one minute
it would take a fraction of a second and the next it would be 20 seconds.
when i run mysql on the same machine i dont see a problem.
please let me know what other info i should post to help diagnose the issue and fix it.

i use ip addresses rather than hostnames to connect so skip-name-resolve shouldn't be nessesary?

my.cnf

[mysqld]
server-id=1
log-bin
datadir=/home/mysql
socket=/var/lib/mysql/mysql.sock
skip-locking
max_connections = 500
key_buffer = 256M
max_allowed_packet = 1M
table_cache = 256
sort_buffer_size = 1M
read_buffer_size = 1M
read_rnd_buffer_size = 4M
myisam_sort_buffer_size = 64M
thread_cache_size = 8
query_cache_size= 16M
default-character-set=latin1
#bind-address=192.168.1.10
[mysqld_safe]
err-log=/var/log/mysqld.log
open_files_limit = 8192
long_query_time=3
log-slow-queries=/var/log/slow-mysql.log
[mysqldump]
quick
max_allowed_packet = 16M

[myisamchk]
key_buffer = 64M
sort_buffer = 64M
read_buffer = 16M
write_buffer = 16M

[mysql.server]
user=mysql


httpd.conf :

ServerTokens OS
ServerRoot "/etc/httpd"
PidFile run/httpd.pid
Timeout 120
KeepAlive Off
MaxKeepAliveRequests 100
KeepAliveTimeout 5
<IfModule prefork.c>
StartServers 8
MinSpareServers 5
MaxSpareServers 20
ServerLimit 100
MaxClients 100
MaxRequestsPerChild 400
</IfModule>


......



Edited 1 time(s). Last edit at 09/12/2007 08:57AM by adrian murphy.