Re: multiple writes in a short period cause db instability

[David Hawes <dhawes@vt.edu>]

I ran into a similar issue when I was testing an overlay that I wrote.  slapd 
would reach some kind of deadlock and would not accept any requets.  I 
tracked it down to slap_get_commit_csn and then noticed that 2.2.17 was 
released.  A quick glance at the changes revealed:  Fixed slapd overlays CSN 
CTX bug (ITS#3288).  I have since been testing with 2.2.17 and have not hit 
any deadlocks (after tens of millions of entries).  I hope this works for you 
as well.

dave

On Wednesday 22 September 2004 01:06 pm, Jonathan Higgins wrote:
> working on a new build with the following software:
> OpenLDAP-2.2.15
> db-4.2.52 w/ patches
> (other components are included but do not relate to the current issue:
> cyrus-sasl-2.1.19, heimdal-0.6, openssl-0.9.7d)
>
> build on the following hardware:
> OS= Redhat 7.3
> processor=2.8ghz
> memory=1gig
>
>
> some of the config info that I am using:
> DB_CONFIG:
> set_cachesize 0 300000000 10
> set_lg_regionmax 262144
> set_lg_bsize 2097152
>
> partial slapd.conf(db portion):
> threads 20
> database        bdb
> lastmod on
> checkpoint 1024 5
> cachesize 30000
> idlcachesize 30000
>
> some of these were guessed, based on hardware and software
> configurations of others that I found on the net using similar
> hardware.
>
> Reads are super fast.. I mean stupid fast! .. never seen it perform
> this well.. ever.
> a db_stat -m in the database directory shows:
> 357MB 644KB 540B        Total cache size.
> 10      Number of caches.
> 35MB 784KB      Pool individual cache size.
> 0       Requested pages mapped into the process' address space.
> 35M     Requested pages found in the cache (100%).
>
> Writes work, as long as its only a few ... but if I try to add 100 user
> accounts using ldapadd -f file.ldif .. it bombs out fairly quickly, with
> no obvious errors(loglevel -1).  The technical term "bombs" is defined
> as, slapd stops responding, but is still running.
>
> I need to run a db_recover on the db before slapd will come up
> properly.
>
> what other information would I need to provide so that I or someone
> else can help me diagnose this problem.
>
> Thanks
>
>
> Jonathan Higgins
> IT R&D Project Manager
> Kennesaw State University
> jhiggins@kennesaw.edu