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sortvals oddities - with more information and hopefully to the right list

  We are using sortvals on both member and memberUid. We have been
seeing duplicate member/memberUid attributes on some objects that have
been modified (as well as a lack of sorting on those attributes). It
seemed that there was a correlation between modifies to objects that
experienced deadlocks and the objects that had duplicate
member/memberUid attributes on them. We put the seqmod overlay in
place - and this reduced the number of occurrences of the issue but
did not eliminate them.

Upon further investigation, I discovered that it was possible to
bypass the sorting behavior if the object was not created with an
instance of the attribute with sorting enabled as a part of it.

It would seem that attr_merge() (in attr.c) should have something like this:

        if ( *a == NULL ) {
                *a = attr_alloc( desc );
                if (desc->ad_type->sat_flags & SLAP_AT_SORTED_VAL) {
                  (*a)->a_flags |= SLAP_ATTR_SORTED_VALS;
        } else {

Further pursuing the issue, I started to focus on the index deletion
code that was changed as a part of ITS#5183. Specifically, the
portion of code within bdb_modify_internal() (in back-bdb/modify.c)
that is commented:

                  /* Move deleted values to end of array */

This code modifies save_attrs, which is actually apparently a pointer
to memory that resides within the cache. If a deadlock occurs, these
changes are not reverted, thereby corrupting the entry in the cache. I
replaced this code with the pre-ITS#5183 code and I am no longer able
to 'break' the object and insert duplicate member/memberUids.

I also found it surprising that the call to bdb_idl_cache_del() in
bdb_idl_delete_key() in back-bdb/idl.c occurred prior to any calls to
the database?

I can answer any questions about the specifics of the environment
in which where we are seeing this - it is a somewhat difficult problem to
reproduce outside of our production environment. I'm not terribly
familiar with the code - I'm looking to see if I have collected enough
data here to open an ITS to have this fixed. (or if I'm just way off base)



Andrew W. Elble
Infrastructure Engineer, Communications Technical Lead
Rochester Institute of Technology
PGP: BFAD 8461 4CCF DC95 DA2C B0EB 965B 082E 863E C912

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