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Re: (ITS#3647) Segmentation fault search sublevel back-hdb
Thanks for the report, it sounds like you're right.
re:2 - yes, this makes sense. The only way for an ID to appear in the
intersection would be if there was a loop in the tree structure, which
cannot occur here. (Loops due to aliases are handled elsewhere.) If you
can submit the code you have, I'll take a look at integrating it. (See
the submission guidelines at
>Version: 2.2.24 & 2.2.17
>OS: linux / debian
>Submission from: (NULL) (18.104.22.168)
>1 - Segmentation Fault Problem
>backend is hdb. (We tested it and reproduced it on 2.2.24 and 2.2.17, We didn't
>test it on other version.)
>We work on a node (not the root node) where there is more than 300.000
>sub-entries with 17.000 direct children.
>When we do a search sub-level ( doesn't matter the filter ), slapd crash with
>So I added trace and it seems that the problem appears in the bdb_idl_union
>This function is called in hdb_dn2idl_internal (line 1054).
>bdb_idl_union( cx->ids, cx->tmp );
>cx->tmp is declare as ID tmp[BDB_IDL_DB_SIZE] on dn2id_cookie
>and in bdb_idl_union the limit is define with BDB_IDL_UM_SIZE.
>I replace BDB_IDL_DB_SIZE by BDB_IDL_UM_SIZE on the dn2id_cookie struct
>declaration, and it seems to fix the problem.
>Could you tell me if I'm wrong ?
>2 - Performance Problem.
>A search (with indexed filter attributes) on this node took 40s on hdb against >
>0.5s on bdb.
>With help of trace, we saw that the most of the time is spent on bdb_idl_union.
>(idlcachesize is set to 80.000)
>My hypothese is that the intersection between cx->ids and cx->tmp are always
>empty when we descend the tree recursively? I don't known if it's really right,
>but I replace the bdb_idl_union by a bdb_idl_append function which just append
>cx->tmp to cx->ids. I sorted cx->ids afterward.
>The obtained performance (with our data) is near bdb performance, on our data we
>obtain the same search result for some test case.
>But i'm afraid of the regresion risk. Could you tell me if my hypothese is good
-- Howard Chu
Chief Architect, Symas Corp. Director, Highland Sun
Symas: Premier OpenSource Development and Support