Re: Upgrade from 9.4 -> 9.5, FreeBSD 10.2-STABLE, fails on initdb - Mailing list pgsql-general

From Karl Denninger
Subject Re: Upgrade from 9.4 -> 9.5, FreeBSD 10.2-STABLE, fails on initdb
Date
Msg-id 56B39AB1.3050705@denninger.net
Whole thread Raw
In response to Re: Upgrade from 9.4 -> 9.5, FreeBSD 10.2-STABLE, fails on initdb  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general


On 2/4/2016 12:28, Tom Lane wrote:
Karl Denninger <karl@denninger.net> writes:
$ initdb -D data-default
...
creating template1 database in data-default/base/1 ... FATAL:  could not
create semaphores: Invalid argument
DETAIL:  Failed system call was semget(2, 17, 03600).
Hmm.  On my Linux box, "man semget" says EINVAL means
      EINVAL nsems  is less than 0 or greater than the limit on the number of             semaphores per semaphore set (SEMMSL), or a semaphore set corre-             sponding  to  key  already  exists, and nsems is larger than the             number of semaphores in that set.

which agrees with the POSIX spec.  Is FreeBSD the same?

Proceeding on the assumption that it is ...

17 is the same nsems value we've been using for donkey's years, so the
SEMMSL aspect of this seems unlikely to apply; what presumably is
happening is a collision with an existing semaphore's key.  Our code is
prepared for that, but it expects a different error code in such cases,
either EEXIST or EACCES:
       /*        * Fail quietly if error indicates a collision with existing set. One        * would expect EEXIST, given that we said IPC_EXCL, but perhaps we        * could get a permission violation instead?  Also, EIDRM might occur        * if an old set is slated for destruction but not gone yet.        */

It sounds like your kernel is returning EINVAL in preference to any of
those codes, which would be pretty broken.  I do not want to make our code
treat EINVAL as meaning we should retry with a different key, because if
the problem is indeed the SEMMSL limit, we'd be in an infinite loop.

You can probably get past this for the moment if you can remove the
semaphore set with key 2, but I'd advise filing a FreeBSD kernel
bug about their choice of errno.
		regards, tom lane

That sounds like it well may be the problem....

s        65564            2 --rw-rw-rw- www      www      www      www                 3 12:29:14  7:56:04


Oh look, the web server process has a semaphore set out with a "2" key....

I've filed a bug report.  Thanks.

--
Karl Denninger
karl@denninger.net
The Market Ticker
[S/MIME encrypted email preferred]
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