Why slapd use so many system resource?

[Wang Penghui <wangpenghui@realss.com>]

Hi all:

I have a ldapserver which hosts about one hundred entries, everything 
works well until yesterday. I found that it could not be access by ldap 
client such as phpldapadmin. I checked the LDAP server status with some 
tools such as "top" and "ps aux | grep slapd"  and found that LDAP 
server has use almost all the system resources.
Here is the result:
#ps aux | grep slapd

ldap      6973  0.0  0.5 175892 5264 ?       S    17:52   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      6975  0.0  0.5 175892 5264 ?       S    17:52   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      6976  0.0  0.5 175892 5264 ?       S    17:52   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      7021 99.9  0.5 175892 5264 ?       R    17:53 209:36 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      7069  0.0  0.5 175892 5264 ?       S    17:55   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      7235  0.0  0.5 175892 5264 ?       S    17:59   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      7252  0.0  0.5 175892 5264 ?       S    18:00   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      7282  0.0  0.5 175892 5264 ?       S    18:01   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      7299  0.0  0.5 175892 5264 ?       S    18:01   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      7429  0.0  0.5 175892 5264 ?       S    18:05   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap      9811  0.0  0.5 175892 5264 ?       S    20:15   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10237  0.0  0.5 175892 5264 ?       S    20:37   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10249  0.0  0.5 175892 5264 ?       S    20:38   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10424  0.0  0.5 175892 5264 ?       S    20:47   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10477  0.0  0.5 175892 5264 ?       S    20:49   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10478  0.0  0.5 175892 5264 ?       S    20:49   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10502  0.0  0.5 175892 5264 ?       S    20:50   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10523  0.0  0.5 175892 5264 ?       S    20:51   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
ldap     10599  0.0  0.5 175892 5264 ?       S    20:57   0:00 
/usr/lib/openldap/slapd -u ldap -g ldap
hartt    11105  0.0  0.0  1500  516 pts/1    S    21:22   0:00 grep slapd

When i stop the slapd daemon, i found that all the process still in "ps 
aux".
I have to kill all the process manually.

After restart, the condition will appear again.

Here is my configuration files slapd.conf
========Slapd.conf==========
include         /etc/openldap/schema/core.schema
include         /etc/openldap/schema/corba.schema
include         /etc/openldap/schema/cosine.schema
include         /etc/openldap/schema/inetorgperson.schema
include         /etc/openldap/schema/java.schema
include         /etc/openldap/schema/misc.schema
include         /etc/openldap/schema/nis.schema
include         /etc/openldap/schema/openldap.schema
include         /etc/openldap/schema/qmail.schema
include         /etc/openldap/schema/phpgwcontact.schema
include         /etc/openldap/schema/phpgwaccount.schema
pidfile         /var/run/openldap/slapd.pid
argsfile        /var/run/openldap/slapd.args

database        bdb
suffix          "dc=xxx,dc=com"
rootdn          "cn=Manager,dc=xxx,dc=com"
rootpw          password
directory       /var/lib/openldap-data
index   objectClass     eq

Any mistake?

My version is openldap-2.1.26.

Thanks in advance!

Wang Penghui