Re: LDAP authenticated session terminated by signal 11: Segmentation fault, PostgresSQL server terminates other active server processes

Thomas Munro <thomas(dot)munro(at)gmail(dot)com> writes:
> On Wed, Feb 27, 2019 at 3:57 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> If pthread_is_threaded_np(), or something equivalent, is widely available
>> then it might be all right to try solving this going forward by switching
>> to libldap_r and seeing if anyone hits those cross-checks. I'd be afraid
>> to risk it in the back branches though ...

> Hmm. Well here is a new data point: it looks like the Red Hat family
> of distributions is in the process of making the same decision as
> Debian (namely: to expunge the non-MT variant, because it bites
> various projects in the same way that it bites us), but they haven't
> quite hasn't pulled the trigger yet:
> https://fedoraproject.org/wiki/Changes/OpenLDAPwithoutNonthreadedLibraries

Interesting, but that's going to be a very slow change. That says they'll
pull the trigger in Fedora 30, which I think is due to be released this
spring --- but it won't show up in RHEL till the next major release (8
or maybe even 9 at this point), and the existing major releases have got
10-year support lifespans.

> I don't see pthread_is_threaded_np() on any non-Apple systems in my
> lab.

Yeah, I thought that might be a Mac thing. I wonder if POSIX has any
usable equivalent.

> Clearly libdap_r is *capable* of creating threads: it contains a
> function ldap_pvt_thread_create(), and we can see that slapd and other
> OpenLDAP things use that, but AFAICT that's a private facility not
> intended for end users to call, so there's no danger if you just use
> the documented LDAP client API.

That seems promising, but I'd sure be happier if we could cross-check
that there's still just one thread at the completion of authentication.

regards, tom lane