strange memory leak (in ldb?)

[Kamen Mazdrashki]

On Thu, Nov 4, 2010 at 19:30, Stefan (metze) Metzmacher <metze at samba.org> wrote:
> Hi Tridge,
>
> I noticed that we have seem to have a memory leak somewhere...
>
> I have the following setup a domain with ~ 20000 objects (users, groups,
> computers).
>
> When I start 'samba' the heap looks fine.
>
> full talloc report on 'null_context' (total 1287675 bytes in 31491 blocks)
> ...
>
> while the heap section is /proc/<pid>/smaps looks like this:
>
> 00612000-01fb4000 rw-p 00000000 00:00 0
>  [heap]
> Size:              26248 kB
> Rss:               26092 kB
> Pss:               13332 kB
> Shared_Clean:          0 kB
> Shared_Dirty:      25520 kB
> Private_Clean:         0 kB
> Private_Dirty:       572 kB
> Referenced:        26092 kB
> Swap:                  0 kB
> KernelPageSize:        4 kB
> MMUPageSize:           4 kB
>
> After doing an DRS-RPC-DSSYNC against samba / or letting a windows dc
> replicate from us.
>
> It looks like:
>
> full talloc report on 'null_context' (total 1293104 bytes in 31552 blocks)
> ... (not much different, there're small leaks I'm currently fixing)
>
> But the heap looks like this now:
>
> 00612000-20854000 rw-p 00000000 00:00 0
>  [heap]
> Size:             526600 kB
> Rss:              526568 kB
> Pss:              524624 kB
> Shared_Clean:          0 kB
> Shared_Dirty:       3888 kB
> Private_Clean:         0 kB
> Private_Dirty:    522680 kB
> Referenced:       526568 kB
> Swap:                  0 kB
> KernelPageSize:        4 kB
> MMUPageSize:           4 kB
>
> About 20x more than before the replication.
>
> I think I had something similar in our wins server, when replication a
> large database
> and the leak was triggered by ldb_search(), but I never figured out why.
> Eevent valgrind's massif didn't help to track it down.
>
> Do you have any idea what the problem is, maybe a glibc malloc bug?
>
Perhaps I don't know how exactly how memory manager works under linux,
but does it reclaims freed memory right away?
I.e. if you make another DSSYNC test, will it increase memory usage again?


-- 
CU,
Kamen