NITB hangs if many subscribes and/or subsr. exists with empty extension in hlr

Alexander Chemeris alexander.chemeris at
Mon Jul 25 15:11:07 UTC 2016

Hi Keith,

I can confirm that OpenBSC becomes extremely slow and almost hangs
after a certain amount of subscribers or a large number of SMS (30,000
subs sounds like a number it should happen). I'm not 100% certain, but
I think this is the real reason and not the empty extension. If you
have a copy of the HLR - you should be able to reproduce that just by
starting an OpenBSC with this HLR database.

On Mon, Jul 25, 2016 at 8:19 AM, Keith <keith at> wrote:
> Hi All,
> On one of our sites osmo-nitb was hanging a few seconds after startup. It
> took me a while to track it down, and I'm sorry I do not have log output as
> it has gone to scroll buffer heaven, and I do not want to break the system
> again right now to get another output, but I can say more or less what
> happens.
> If I see it again, I'll be sure to capture full debug log. I also have a
> backup of the state of the offending hlr, so I can bring it up locally and
> see if I can replicate and send the log.
> In fact, there was nothing out of the ordinary in the log anyway before nitb
> simply stops responding. (CTRL-C still shuts down cleanly if would seem)
> This 'bad' hlr has some 30,815 subscriber entries, one of them has empty
> string for extension.
> (We normally never get to anything near 30,000 as we purge inactive
> subscribers regularly, but the blank extension had broken our purge job)
> On this blank extension issue, i'm not sure it coincides with the hang, but
> I noted this error followed by DBI traceback from here:
> Error was non unique value for column extension, which makes sense of
> course, as we don't give it a value.
> Also seems we don't recover from this, as db_subscriber_alloc_exten() will
> never be called?
> I deleted some 28,000 subscriber entries that were not commissioned users,
> and the nitb then functions, so I'm at a loss to know where it might have
> been actually stuck, or if it might be related to the blank extension, or to
> the large amount of subscriber entries, or something else.
> Maybe it's obvious to somebody. I have of course deleted the blank extension
> entry now from the hlr.
> Thanks!
> Keith.

Alexander Chemeris.
CEO, Fairwaves, Inc.

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