I can confirm that I am reproducing the same error with Apache HTTPD 2.4.46 on IBM AIX 7.2 (7200-04-02-2016). 

Has any effort been done to diagnose/patch this issue?

(In reply to Randal T. Rioux from comment #1)
> I can confirm that I am reproducing the same error with Apache HTTPD 2.4.46
> on IBM AIX 7.2 (7200-04-02-2016). 
> 
> Has any effort been done to diagnose/patch this issue?


Looks like an APR issue not an HTTPD issue. This report has no info about the APR build other than that it must have used gcc.


Does it fail with a modern gcc?  Can you find libgcc at runtime?

Here is my process, with versions listed. GCC is 8.3.0 and all necessary libraries appear to be located okay. Thanks for helping out!

# export CFLAGS="-mcpu=power7 -pipe -O2"
# CXXFLAGS=$CFLAGS
# export RM="/usr/bin/rm -f"
# export AR="/usr/bin/ar"
# export LDFLAGS="-Wl,-brtl"

# cd /usr/src
# wget https://mirrors.ocf.berkeley.edu/apache/apr/apr-1.7.0.tar.bz2
# tar xvfj apr-1.7.0.tar.bz2
# rm apr-1.7.0.tar.bz2 && cd apr-1.7.0
# ./configure --enable-threads
# make && make install

# cd /usr/src
# wget https://mirrors.ocf.berkeley.edu/apache/apr/apr-util-1.6.1.tar.bz2
# tar xvfj apr-util-1.6.1.tar.bz2
# rm apr-util-1.6.1.tar.bz2 && cd apr-util-1.6.1
# ./configure --with-apr=/usr/local/apr
# make && make install

# cd /usr/src
# wget https://mirrors.ocf.berkeley.edu/apache/httpd/httpd-2.4.46.tar.bz2
# tar xvfj httpd-2.4.46.tar.bz2
# rm httpd-2.4.46.tar.bz2 && cd httpd-2.4.46
# ./configure --enable-so --enable-cache --enable-mem-cache --enable-ssl --enable-dav --with-apr=/usr/local/apr
# make && make install

bash-5.0# /usr/local/apache2/bin/httpd 
exec(): 0509-036 Cannot load program /usr/local/apache2/bin/httpd because of the following errors:
rtld: 0712-001 Symbol __sync_fetch_and_add_8 was referenced
      from module /usr/local/apr/lib/libapr-1.so(), but a runtime definition
      of the symbol was not found.
rtld: 0712-001 Symbol __sync_fetch_and_sub_8 was referenced
      from module /usr/local/apr/lib/libapr-1.so(), but a runtime definition
      of the symbol was not found.
rtld: 0712-001 Symbol __sync_sub_and_fetch_8 was referenced
      from module /usr/local/apr/lib/libapr-1.so(), but a runtime definition
      of the symbol was not found.
rtld: 0712-001 Symbol __sync_val_compare_and_swap_8 was referenced
      from module /usr/local/apr/lib/libapr-1.so(), but a runtime definition
      of the symbol was not found.
rtld: 0712-001 Symbol __sync_lock_test_and_set_8 was referenced
      from module /usr/local/apr/lib/libapr-1.so(), but a runtime definition
      of the symbol was not found.

After a lot of trial and error, I've discovered how vitally important the order of search is for library files.

The following environment variables worked for me (64-bit build), producing a fully functional installation of HTTPD (w/ APR and APR-Utils):

# export CFLAGS="-maix64 -mcpu=power7 -D_LARGE_FILES -pipe -O2 -L/usr/local/lib:/opt/freeware/lib64:/opt/freeware/lib:/usr/lib64:/usr/lib -I/usr/local/include:/opt/freeware/include:/usr/include"
# CXXFLAGS=$CFLAGS
# export RM="/usr/bin/rm -f"
# export AR="/usr/bin/ar -X64"
# export NM="/usr/bin/nm -X64"
# export OBJECT_MODE=64
# export LDFLAGS="-maix64 -Wl,-b64 -Wl,-brtl -Wl,-blibpath:-L/usr/local/lib:/opt/freeware/lib64:/opt/freeware/lib:/usr/lib64:/usr/lib"

apr-utils was configured with this:

./configure --with-apr=/usr/local/apr --with-iconv=/opt/freeware

and HTTPD was configured with this:

./configure --enable-so --enable-ssl --enable-dav --with-apr=/usr/local/apr --with-apr-util=/usr/local/apr --with-pcre=/opt/freeware/bin/pcre-config_64

Hopefully this helps someone else! :-)