RE: BDB Locker

["Howard Chu" <hyc@highlandsun.com>]

> -----Original Message-----
> From: owner-openldap-software@OpenLDAP.org
> [mailto:owner-openldap-software@OpenLDAP.org]On Behalf Of RW

> Hi!
>
> Using BDB 4.5.52 (no patches), OpenLDAP 2.2.11 and Redhat ES
> 3 from time
> to time I get the following
> DB_LOCK_DEADLOCK error's:

> => bdb_dn2id_add: put failed: DB_LOCK_DEADLOCK: Locker killed
> to resolve
> a deadlock -30995
>
> Before moving the database files to a really fast SAN and increasing
> set_lk_max_lockers, set_lk_max_locks,
> set_lk_max_objects and set_tx_max the error's occured more often. But
> they are still occuring. I believe
> that this deadlocks are sometimes cases OpenLDAP to crash.
> Now I have seen that there are two patches for BDB available
> which are addressing locking issues.
> Has anyone similar problemes with this kind of deadlock's? Would
> applying the BDB patches help to
> solve this deadlock problems? Any experience?

The first patch is definitely needed; I have never seen OpenLDAP run into the
situation fixed by the second patch but it's probably good to include it for
completeness' sake.

Deadlocks are a fact of life in BDB. They are not fatal, back-bdb retries the
failed operations automatically.

I don't know what kind of SAN you're using, but in general, BDB doesn't work
with remote filesystems. If your SAN supports byte-range locking and
memory-mapping it should be OK, but that's something to check.

  -- Howard Chu
  Chief Architect, Symas Corp.       Director, Highland Sun
  http://www.symas.com               http://highlandsun.com/hyc
  Symas: Premier OpenSource Development and Support