loading multi threaded library into executable enabled for single thread

[Barry Andrews]

Yes, the exe is tclsh. I understand that linking tclsh with libpthread is
what would work. However this is very impractical. A user of my library
shouldn't have to rebuild their tclsh to match my library specs. Another
option would be to ship tclsh with my lib, but that also is a little weird.
It seems like the only somewhat practical option I have is to use
LD_PRELOAD, which is also weird but better than nothing.

On Fri, Sep 12, 2008 at 11:45 AM, Jeremy Chadwick <koitsu at freebsd.org>wrote:

> On Fri, Sep 12, 2008 at 11:00:18AM -0400, Barry Andrews wrote:
> > Thanks for the links! But I'm not sure what any of this has to do with
> > this particular issue. I have an exe that does not use threads that
> > loads a lib that is linked with libpthread. Why does different threading
> > implementations affect what I am seeing here? Is there no way for this
> > to work in FreeBSD v5.5? Why would this go away if I upgraded to 6.x or
> > better?
>
> You're confusing me.  Earlier you said:
>
> >>>>>>> I have a multi-threaded library that is linked against libpthread.
> >>>>>>> When I
> >>>>>>> load this lib into a tclsh process on FreeBSD, I get this error,
>
> So what is "the exe?"  Are you referring to tclsh?  If so, you need to
> rebuild tclsh from source to link with libpthread.  If not, you need to
> contact whoever provided the binary and ask them to rebuild it from
> source.
>
> Additionally, please ensure that the tclsh binary is linked to the same
> version of libpthread library as your own library.  You want to make
> sure they're both built and linked on the same machine (from the same
> source code) if possible; the simple ".so.X" versioning method works
> great for major changes, but there are often minor changes that don't
> result in "X" being increased.
>
> I'm getting the impression that the tclsh binary you have was not built
> on the same machine / from the same source as what your library (the one
> linked with libpthread) was.
>
> > Jeremy Chadwick wrote:
> >> On Fri, Sep 12, 2008 at 09:26:37AM -0400, Barry Andrews wrote:
> >>
> >>> I don't understand. If it was not broken, then why did it change in
> later
> >>> FreeBSD versions?
> >>>
> >>
> >> I should be more explicit: the threading library and implementations
> >> have changed over time.  There was libc_r, then there was libthr, then
> >> there was libkse.  This is what we call "evolution".  :-)
> >>
> >> http://www.unobvious.com/bsd/freebsd-threads.html
> >> http://kerneltrap.org/node/624
> >> http://www.freebsd.org/kse/
> >>
> >> The gcc -pthread flag is still there on present-day FreeBSD (6 through
> >> HEAD), and *should* be used.  You can choose not to use it but you must
> >> ensure during linktime that you explicitly link to -lpthread.
> >>
> >>
> >>> On Fri, Sep 12, 2008 at 9:10 AM, Jeremy Chadwick <koitsu at freebsd.org>
> wrote:
> >>>
> >>>
> >>>> On Fri, Sep 12, 2008 at 07:41:14AM -0400, Barry Andrews wrote:
> >>>>
> >>>>> Do you know if this is documented in Release Notes or Known Issues or
> >>>>> somewhere?
> >>>>>
> >>>> Why would it be an "issue"?  gcc -pthread and libpthread linking is
> >>>> documented pretty much everywhere on the web.  There isn't anything
> >>>> broken about it, it's how it's done on older FreeBSD.
> >>>>
> >>>> Note that all of this has significantly changed in later FreeBSD
> >>>> versions, and that the 5.x series was deprecated a very long time ago.
> >>>>
> >>>>
> >>>>>> On Thu, 11 Sep 2008, Barry Andrews wrote:
> >>>>>>
> >>>>>>
> >>>>>>> Hi All,
> >>>>>>>
> >>>>>>> I have a multi-threaded library that is linked against libpthread.
> >>>>>>> When I
> >>>>>>> load this lib into a tclsh process on FreeBSD, I get this error,
> >>>>>>> "Recurse on
> >>>>>>> private mutex". and crash. I understand that I can have this issue
> >>>>>>> when the
> >>>>>>> executable is not linked against libpthread but one of the loaded
> >>>>>>> libs is.
> >>>>>>> Basically, it thinks it's in single threaded mode.
> >>>>>>>
> >>>>>> This must be an older version of FreeBSD.  I think you must
> >>>>>> link your application (tclsh or whatever) against libpthread
> >>>>>> in order for this to work.  The libc functions won't get properly
> >>>>>> overloaded by their equivalents in libpthread unless you do
> >>>>>> this.
> >>>>>>
> >>>> --
> >>>> | Jeremy Chadwick                                jdc at parodius.com|
> >>>> | Parodius Networking                       http://www.parodius.com/|
> >>>> | UNIX Systems Administrator                  Mountain View, CA, USA |
> >>>> | Making life hard for others since 1977.              PGP: 4BD6C0CB |
> >>>>
> >>>>
> >>>>
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> >>
> >>
> >
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>
> --
> | Jeremy Chadwick                                jdc at parodius.com |
> | Parodius Networking                       http://www.parodius.com/ |
> | UNIX Systems Administrator                  Mountain View, CA, USA |
> | Making life hard for others since 1977.              PGP: 4BD6C0CB |
>
>