Threadiing Problems on AIX 4.3.3 ML-11 with gcc 3.2.3 (g++)

[Markus dot Schaeffer at np-gmbh dot com]

Hello folks,

> I assume you mean that you are using the native AIX linker, but
>invoking "g++" to perform the link, not invoking "ld" directly.
>Otherwise, using "-Wl," in the LDFLAGS could not possibly work.

Yes indeed.

> Why are you adding "-fexceptions"?  The GNU C++ Compiler defaults
> to exceptions on.  This is CXXFLAGS, not CFLAGS.

At the moment I'am not shure that threads are the trouble makers.

###
Because an ldd gives the following info:
$ ldd ./server
/usr/lib/librtl.a(shr.o)
/usr/lib/libdl.a(shr.o)
/pkg/dev01/tools/compiler/gcc/lib/libgcc_s_pthread.a(shr.o) -> Is this a
static lib? Are there problems with exception handling?
/pkg/dev01/tools/compiler/gcc/lib/libgcc_s.a(shr.o)         -> "" ""
Thers's another lib in gcc libgcc_eh.a eh -> exception handling/invoked by
-shared-libgcc
/pkg/dev01/tools/compiler/gcc/lib/libstdc++.a(libstdc++.so.5)
/usr/lib/libpthreads.a(shr.o)
/usr/lib/libpthreads_compat.a(shr.o)
/usr/lib/libcrypt.a(shr.o)
/usr/lib/libc.a(shr.o)
/usr/lib/libpthreads.a(shr_comm.o)
/usr/lib/libpthreads.a(shr_xpg5.o)
/tmp/MS/0.07/libbase/aix/xerces/libxerces-c1_6_0.a
./server
$

And ldd of my shared lib gives me the following:

$ ldd ./libserviceconnectorarchive.a
/pkg/dev01/tools/compiler/gcc/lib/libgcc_s_pthread.a(shr.o)
/pkg/dev01/tools/compiler/gcc/lib/libgcc_s.a(shr.o)
/pkg/dev01/tools/compiler/gcc/lib/libstdc++.a(libstdc++.so.5)
/usr/lib/libpthreads.a(shr.o)
/usr/lib/libpthreads_compat.a(shr.o)
/usr/lib/libcrypt.a(shr.o)
/usr/lib/libc.a(shr.o)
/usr/lib/libpthreads.a(shr_comm.o)
/usr/lib/libpthreads.a(shr_xpg5.o)
/tmp/MS/0.07/libbase/aix/xerces/libxerces-c1_6_0.a
./libserviceconnectorarchive.a
$

And at least my xerces build:
$ ldd ./libxerces-c1_6_0.a
/pkg/dev01/tools/compiler/gcc/lib/libgcc_s_pthread.a(shr.o)
/pkg/dev01/tools/compiler/gcc/lib/libgcc_s.a(shr.o)
/pkg/dev01/tools/compiler/gcc/lib/libstdc++.a(libstdc++.so.5)
/usr/lib/libpthreads.a(shr.o)
/usr/lib/libpthreads_compat.a(shr.o)
/usr/lib/libcrypt.a(shr.o)
/usr/lib/libc.a(shr.o)
/usr/lib/libpthreads.a(shr_comm.o)
/usr/lib/libpthreads.a(shr_xpg5.o)
./libxerces-c1_6_0.a
###


> I assume LDFLAGS is for the application and SHARED_LDFLAGS is for
> the shared library.

Yes indeed.

> Why does LDFLAGS contain "-Wl,-brtl", but SHARED_LDFLAGS does not
> contain "-Wl,-G"?  Does the application use some other shared library
with
> System-V semantics?  Not all shared libraries need to be linked with
> "-Wl,-G", but "-Wl,-brtl" serves no purpose unless the shared library was
> linked with "-Wl,-G".  If you are using "-Wl,-brtl" for the linker to
> notice shared libraries with the file suffix ".so", don't do that.  AIX
> shared libraries normally are archives (ar command) of shared objects.
> You can use the ".a" suffix directly on the shared object instead of
> creating an archive.  Using the ".so" suffix for non-System-V semantics
> shared objects just creates confusion.

Ok, I did my homework after you told me that twice. ( See my makefile below
!)

> Also, I am concerned that you need to add "-Wl,-bh:5" to your link
> line.  If you need to change the linker halt level from the default,
> something is wrong.

I get level 4 Warnings of duplicated symbols. (Check my makefile, it
deleted -> you are rigth this is not very clever)

> You have not mentioned what errors are produced by the AIX linker
> requiring raising the halt level and you have not mentioned what
"problem"
> you encounter if your server does many calls.

No linking problems. (Just warnings!)

> While AIX provides a thread-safe C library and GCC libstdc++-v3
> strives to be thread safe, libstdc++-v3 may not interact with AIX libc in
> a thread-safe manner.  libstdc++-v3 makes assumptions based on GNU libc
> that are not correct on all platforms.  For instance, there are known
> issues with libstdc++-v3 use of setlocale() in I/O functions.  Does your
> shared library perform threaded I/O?

Yes...!?

> User-written code interacting with libstdc++-v3 must follow the
> SGI thread-safety rule, which basically says that the direct use of any
> global library object (e.g. std::cout is global) or non-local object
> returned from the library shared amongst user threads, must be protected
> by a mutex or similar by the user.

It's a hard thing but I will check this. I got the job for 2 weeks and this
is a mess anyway.

### MAKEFILE ###
CXXFLAGS=   -c -g \
            -Wno-deprecated \
            -pthread

LDFLAGS=    -pthread \
            -Wl,-brtl \
            -Wl,-bnoquiet \
            ${XERCESC_LDFLAGS} \
            -ldl

SHARED_LDFLAGS=   -pthread -shared \
                  -Wl,-bE:symbols.exp \
                  -Wl,-binitfini:init:fini:1 \ I've changed that to "0" but
it does ot make any difference
                  -Wl,-G \
                  -Wl,-bnoquiet \
                  ${XERCESC_LDFLAGS} \
                  -ldl
####

Regards
Mattey

P.S.: Thanks for all the good and fast replys David. It's not working yet
but any advice was worth a lot to me.