According to Boris Gubenko from the HP-UX compiler
development team, it is illegal to link with -lpthread
if the sources are not compiled with -mt. However, this
is exactly what happens during Python installation, e.g.:

        cc -Ae -c  -DNDEBUG -O  -I. -I./Include  
-DPy_BUILD_CORE -o Python/compile.o Python/compile.c
...
         aCC  -Wl,-E -Wl,+s -o python \
                        Modules/python.o \
                        libpython2.5.a -lnsl -lrt -ldld
-ldl  -lpthread   -lm  

This illegal combination of compilation and link flags
eventually results in obscure runtime failures
(segfault, abort) while running Boost.Python C++
extensions. These failures go away if Python is
installed with, e.g.:

env CXX="aCC -mt" BASECFLAGS="-mt" ./configure
--without-gcc

I suggest changing the configure/make files to always
include "-mt" if threading is enabled.

BTW: The same issue already exists for Python 2.4.

Cheers,
        Ralf