Re: Openldap overloading

[Howard Chu <hyc@symas.com>]

Nick Milas wrote:
> Hi,
>
> I am running a v2.4.31 consumer on CentOS 5.8 to serve user accounts
> (and aliases) on a Postfix mail server running locally. It has been
> running for a long time without problems.
>
> Today, after a user sent (on 14:53:39) a mass mail (through a group
> alias, implemented using ldap dynlist), Postfix stalled and the server
> (a VM under KVM) became overloaded. I noticed that openldap was using
> all the cpu:
>
> # top
> top - 15:30:01 up 81 days,  2:11,  1 user,  load average: 113.58,
> 114.36, 104.02
> Tasks: 460 total,   3 running, 457 sleeping,   0 stopped,   0 zombie
> Cpu(s): 98.9%us,  0.0%sy,  0.0%ni,  0.0%id,  0.0%wa,  1.1%hi, 0.0%si,
> 0.0%st
> Mem:   3089988k total,  3074912k used,    15076k free,    12180k buffers
> Swap:  2064376k total,       92k used,  2064284k free,  1909976k cached
>
>     PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+ COMMAND
>    2209 ldap      18   0  577m  17m 8952 S 93.4  0.6  55:03.67 slapd
> ...

Your load average was really 113? I don't see any "threads" setting in your 
config. By default slapd only uses 16 threads, so by itself it could never 
drive the load average above 16. Something else is going quite wrong on your 
system.

Your database looks pretty small. But still, I see no cachesize configuration 
in it. That might help. Or just switch to MDB and continue to not worry about 
cache sizes.

> database        hdb
> suffix          "dc=example,dc=com"
> rootdn          "cn=Manager,dc=example,dc=com"
> rootpw          secret
>
> ########
> # ACLs #
> ########
> include      /usr/local/openldap/etc/openldap/acl.conf
>
> directory    /usr/local/openldap/var/openldap-data
>
> index   objectClass              eq,pres
> index   employeeType             pres,eq
> index   cn                       eq,pres,sub
> index   sn,givenname             eq,pres,sub
> index   mail                     eq,pres,sub
> index   uid                      eq,pres
> index   ou                       eq,pres
> index   mailacceptinggeneralid   eq,pres
> index   owner                    eq
> index   entryCSN,entryUUID       eq
> index   vacationActive           eq
> index   associatedDomain         pres,eq,sub
> index   dc                       eq
> index   emailLocalAddress        eq,pres,sub
>
> overlay dynlist
> dynlist-attrset nisMailAlias labeledURI
> dynlist-attrset groupOfURLs labeledURI member
>
> syncrepl rid=111
>           provider=ldaps://ldap.example.com
>           tls_reqcert=never
>           type=refreshAndPersist
>           retry="60 15 180 +"
>           searchbase="dc=example,dc=com"
>           schemachecking=off
>           bindmethod=simple
>           binddn="uid=FullReplAcc1,ou=System,dc=example,dc=com"
>           credentials="mypassword"
>
> database monitor
>
> access to *
>      by dn.exact="cn=Manager,dc=example,dc=com" read
>      by * none
>
> *********************************************************************
>
> # ls -la /usr/local/openldap/var/openldap-data/
> total 14120
> drwxr-xr-x 2 ldap ldap     4096 Sep 28 15:33 .
> drwxr-xr-x 4 ldap ldap     4096 Apr 26 20:56 ..
> -rw-r--r-- 1 ldap ldap     4096 Sep 28 15:33 alock
> -rw------- 1 ldap ldap  1261568 Sep 28 15:32 associatedDomain.bdb
> -rw------- 1 ldap ldap   512000 Sep 28 15:32 cn.bdb
> -rw------- 1 ldap ldap    24576 Sep 28 15:33 __db.001
> -rw------- 1 ldap ldap  1294336 Sep 28 16:12 __db.002
> -rw------- 1 ldap ldap 32776192 Sep 28 16:12 __db.003
> -rw------- 1 ldap ldap  3145728 Sep 28 16:11 __db.004
> -rw------- 1 ldap ldap   729088 Sep 28 16:12 __db.005
> -rw------- 1 ldap ldap    32768 Sep 28 16:11 __db.006
> -rw-r--r-- 1 ldap ldap      924 Apr 26 21:01 DB_CONFIG
> -rw------- 1 ldap ldap      845 Apr 26 20:56 DB_CONFIG.example
> -rw------- 1 ldap ldap    61440 Sep 28 15:32 dc.bdb
> -rw------- 1 ldap ldap   339968 Sep 28 15:33 dn2id.bdb
> -rw------- 1 ldap ldap   212992 Sep 28 15:33 emailLocalAddress.bdb
> -rw------- 1 ldap ldap    20480 Sep 28 15:33 employeeType.bdb
> -rw------- 1 ldap ldap   118784 Sep 28 15:33 entryCSN.bdb
> -rw------- 1 ldap ldap    81920 Sep 28 15:33 entryUUID.bdb
> -rw------- 1 ldap ldap    90112 Sep 28 15:32 givenName.bdb
> -rw------- 1 ldap ldap  2457600 Sep 28 15:33 id2entry.bdb
> -rw------- 1 ldap ldap    24576 Jul  9 13:13 mailacceptinggeneralid.bdb
> -rw------- 1 ldap ldap   212992 Sep 28 15:33 mail.bdb
> -rw------- 1 ldap ldap   266240 Sep 28 15:33 objectClass.bdb
> -rw------- 1 ldap ldap    40960 Sep 28 15:33 ou.bdb
> -rw------- 1 ldap ldap     8192 Sep 28 15:32 owner.bdb
> -rw------- 1 ldap ldap   253952 Sep 28 15:32 sn.bdb
> -rw------- 1 ldap ldap    28672 Sep 28 15:33 uid.bdb
> -rw------- 1 ldap ldap     8192 Sep 25  2011 vacationActive.bdb
>
> ***************************************************************************


--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/