Bug in replication (ITS#1089)

[hekker@netway.at]

Full_Name: Heinz Ekker
Version: 1.2.11
OS: RedHat Linux 6.2
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (195.96.10.34)


We use a heavy loaded directory for authentication purposes. Changes are made to
a master and the data is replicated to (at the moment) two slaves.

One slave, which is under heavy load, shows strange behaviour:
When one entry is inserted and deleted in a short interval, the insert fails,
although the delete succeeded. The entry in the Reject-Log is 'already exists',
when turning on debugging, we see 'id [num] already in cache'. This does not
happen regularly or with any recognizable pattern. Approximately one of a
hundred entries failes thusly.

It seems that deletions are synchronized with the backend (we use LDBM), but not
with the in-memory cache. Or perhaps this is a thread synchronisation problem. 

Our cachesize is increased to:
dbcachesize 52428800
cachesize 100000
Although with much lower values, this does happen too. Same whether
'dbcachenowsync' is specified or not.