Yup, this is it.  If I build it without DSO support, it appears to work.
Of course I build this with mod_php, mod_ssl, mod_perl, and a couple of
custom modules.  So running without DSO support isn't to easy.  I guess
I can attempt to build mod_perl in, but keep DSO support and dynamic
load the rest of the modules.  Will try that.

* Kyle Dawkins (kyle@centralparksoftware.com) [020728 18:58]:
>  Hey Greg et al.
>  
>  I'd betcha your problem is almost certainly caused by your use of DSOs. If
>  you *really* want to prune your system down to see where your bug is, then
>  build apache and mod_perl statically.  There was a very well-known bug that
>  caused DBI to segfault if it was run under a DSO.   Please rebuild your
>  binary and then let us know if that was the problem.
>  
>  Kyle Dawkins
>  Central Park Software
>  http://www.centralparksoftware.com
>  
>  
>  > Okay, I've been staring at this problem for close to 48 hours straight
>  > now and have finally narrowed it down to a set of lines of code.
>  >
>  > So let me first expand.
>  >
>  > I currently have a system running, with Apache 1.3.14 and Mod_Perl 1.24
>  > on Redhat 7.0 (yeah REALLY REALLY ancient) and Perl 5.005003.  It also
>  > has mod_ssl, and several other modules loaded, but for the sake of the
>  > problems I am having, I completely removed those.
>  >
>  > This actually runs perl scripts that connect and talk to (yeah dig
>  > this), Postgres, Mysql, and Informix.  The root of my problems, as I
>  > have finally found, is Informix.
>  >
>  > In our httpd.conf, we utilize a PerlScript directive to preload a bunch
>  > of environment variables, and other stuff at startup.  The script is
>  > pretty nasty and harry, and buried deep within it happened to be a call
>  > to Informix.
>  >
>  > So for the record, the current system (ancient stuff) works.
>  >
>  > So the problems began.  I decided to upgrade to Apache 1.3.26 and
>  > Mod_Perl 1.27 on Debian Woody (3.0) and Perl 5.006001.  I also built all
>  > the other libraries, and than the fun began.
>  >
>  > At first, I just got seg faults attempting to start apache.  But as I
>  > have said above, I have narrowed it down to a set of lines of code that
>  > cause it to fail.
>  >
>  > So if I build Apache 1.3.26 and Mod_perl 1.27 by themselves, using
>  > pretty straight forward options..
>  >
>  > Apache
>  > ------
>  > CC="gcc" > > CFLAGS="-g" > > LIBS="-L/home/grumple/src/test/lib
>  > -L/home/grumple/src/test/system/lib " > > ./configure > > "--prefix=/home/grumple/src/te
st/system" >  > "--enable-module=most" > > "--enable-shared=max" > > "--with-layout=GNU" > > 
"--disable-rule=EXPAT" >  > "$@"
>  > ----------------------
>  >
>  > and
>  >
>  > Mod_perl
>  > --------
>  > perl Makefile.PL PERL_USELARGEFILES=0 PERL_DEBUG=1 USE_APXS=1
>  WITH_APXS=/home/grumple/src/test/system/sbin/apxs EVERYTHING=1
>  INC=/home/grumple/src/test/system/include
>  > ----------------------
>  >
>  > and than my conf
>  >
>  > httpd.conf
>  > ----------
>  > AccessConfig /dev/null
>  > ResourceConfig /dev/null
>  >
>  > LoadModule env_module         libexec/mod_env.so
>  > LoadModule config_log_module  libexec/mod_log_config.so
>  > LoadModule mime_module        libexec/mod_mime.so
>  > LoadModule autoindex_module   libexec/mod_autoindex.so
>  > LoadModule dir_module         libexec/mod_dir.so
>  > LoadModule alias_module       libexec/mod_alias.so
>  > LoadModule access_module      libexec/mod_access.so
>  > LoadModule auth_module        libexec/mod_auth.so
>  > LoadModule setenvif_module    libexec/mod_setenvif.so
>  >
>  > AddModule mod_env.c
>  > AddModule mod_log_config.c
>  > AddModule mod_mime.c
>  > AddModule mod_autoindex.c
>  > AddModule mod_dir.c
>  > AddModule mod_alias.c
>  > AddModule mod_access.c
>  > AddModule mod_auth.c
>  > AddModule mod_setenvif.c
>  >
>  > ServerType standalone
>  > ServerRoot "/home/grumple/src/test/system"
>  >
>  > PidFile        /var/tmp/run/test.pid
>  > LockFile       /var/tmp/test.lock
>  > ScoreBoardFile /var/tmp/test.scoreboard
>  >
>  > Timeout 300
>  > KeepAlive On
>  > MaxKeepAliveRequests 100
>  > KeepAliveTimeout 15
>  > MinSpareServers 2
>  > MaxSpareServers 10
>  > StartServers    3
>  > MaxClients      256
>  > MaxRequestsPerChild 1000
>  >
>  > LoadModule perl_module libexec/libperl.so
>  > AddModule mod_perl.c
>  >
>  > ServerName grumple
>  > Port       6180
>  >
>  > Listen 6180
>  >
>  > ServerAdmin yeah@right
>  > DocumentRoot /home/grumple/src/test/www/htdocs
>  >
>  > <Directory />
>  > Options FollowSymLinks
>  > AllowOverride None
>  > </Directory>
>  >
>  > <Directory "/home/grumple/src/test/www/htdocs">
>  > Options FollowSymLinks
>  > AllowOverride None
>  > Order allow,deny
>  > Allow from all
>  > </Directory>
>  >
>  > DirectoryIndex index.tp index.htm index.html index.cgi
>  > AccessFileName .htaccess
>  > <Files .htaccess>
>  > Order allow,deny
>  > Deny from all
>  > </Files>
>  >
>  > UseCanonicalName On
>  > TypesConfig "/home/grumple/src/test/system/etc/httpd/mime.types"
>  > DefaultType text/plain
>  > HostnameLookups Off
>  > LogLevel warn
>  >
>  > LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\""
>  combined
>  > CustomLog "/var/tmp/logs/test.access" combined
>  > ErrorLog "/var/tmp/logs/test.errors"
>  >
>  > ReadmeName README
>  > HeaderName HEADER
>  >
>  > IndexOptions FancyIndexing
>  > IndexIgnore .??* *~ *# HEADER* README* RCS CVS *,v *,t
>  >
>  > AddEncoding x-compress Z
>  > AddEncoding x-gzip gz
>  >
>  > AddHandler send-as-is asis
>  > AddHandler imap-file map
>  >
>  > BrowserMatch "Mozilla/2" nokeepalive
>  > BrowserMatch "MSIE 4\.0b2;" nokeepalive downgrade-1.0 force-response-1.0
>  > BrowserMatch "RealPlayer 4\.0" force-response-1.0
>  > BrowserMatch "Java/1\.0" force-response-1.0
>  > BrowserMatch "JDK/1\.0" force-response-1.0
>  >
>  > AddHandler cgi-script .cgi
>  > PerlScript /var/tmp/test.pl
>  >
>  > AddType application/x-x509-ca-cert .crt
>  > AddType application/x-pkcs7-crl .crl
>  >
>  > ErrorDocument 404 /index.tp
>  > ----------------------
>  >
>  > And here's the magical part, the test.pl script that causes the problem.
>  >
>  > test.pl
>  > -------
>  > BEGIN {
>  >     unshift(@INC, qw(
>  >         /home/grumple/src/test/lib/perl5
>  >         /home/grumple/src/test/system/lib/perl5
>  >     ));
>  > }
>  >
>  > use strict;
>  >
>  > use DBI;
>  > use DBD::Informix;
>  >
>  > ## informix connection params
>  > $ENV{'INFORMIXDIR'}    ||= '/opt/informix';
>  > $ENV{'INFORMIXSERVER'} ||= 'test_tcp';
>  > $ENV{'LD_LIBRARY_PATH'} .= ":$ENV{'INFORMIXDIR'}/lib";
>  >
>  > my $catalog = 'test';
>  > my $constr = join(':', 'dbi', 'Informix', $catalog);
>  > my $user = 'test';
>  > my $password = 'test';
>  >
>  > my $dbh = DBI->connect($constr,$user,$password);
>  >
>  > $dbh->disconnect();
>  >
>  > 1;
>  > ----------------------
>  >
>  > So all looks good right?  Well it does, other than running above yields
>  > the following crash in GDB.
>  >
>  > Program received signal SIGSEGV, Segmentation fault.
>  > 0x400e7a90 in free () from /lib/libc.so.6
>  > (gdb) bt
>  > #0  0x400e7a90 in free () from /lib/libc.so.6
>  > #1  0x40255d3b in Perl_safefree () from /usr/lib/libperl.so.5.6
>  > #2  0x402705eb in Perl_sv_clear () from /usr/lib/libperl.so.5.6
>  > #3  0x4027088f in Perl_sv_free () from /usr/lib/libperl.so.5.6
>  > #4  0x40274d6f in Perl_sv_vcatpvfn () from /usr/lib/libperl.so.5.6
>  > #5  0x4026a378 in Perl_sv_add_arena () from /usr/lib/libperl.so.5.6
>  > #6  0x4026a434 in Perl_sv_clean_all () from /usr/lib/libperl.so.5.6
>  > #7  0x40219b75 in perl_destruct () from /usr/lib/libperl.so.5.6
>  > #8  0x401bbb77 in perl_shutdown (s=0x0, p=0x0) at mod_perl.c:294
>  > #9  0x401bc507 in mp_dso_unload (data=0x8094bdc) at mod_perl.c:489
>  > #10 0x08050c39 in run_cleanups (c=0x80a06cc) at alloc.c:1713
>  > #11 0x0804f2d5 in ap_clear_pool (a=0x8094bdc) at alloc.c:538
>  > #12 0x08060bfc in standalone_main (argc=6, argv=0xbffffac4) at
>  http_main.c:5058
>  > #13 0x080615cc in main (argc=6, argv=0xbffffac4) at http_main.c:5448
>  >
>  > The test.pl script works fine by it's self.  Turning on full PERL
>  > debugging/tracing yields that the actual script has fully finished, and
>  > that it's in the tear down of the actualy perl stuff that this failure
>  > is coming from.   Not from the script per se.  But it is the script that
>  > is causing this problem.  Commenting out the connect and disconnect
>  > lines causes the server to startup and function just fine.
>  >
>  > So I'm not quite sure what to do.  I know I can get my entire system
>  > working if I don't make the calls to Informix at startup (it appears
>  > it's purely the connect that causes the error (whether it's a good
>  > connect or not, I tried giving it a bogus password, and it still
>  > crashes)), but well that's kind of a pain in the butt.
>  >
>  > So if anyone has ANY clues, it would be sincerely appreciated, as I need
>  > sleep, and I also would love to get this working.
>  >
>  > Thanks a ton in advance.
>  >
>  > Greg
>  >
>  >
>  > --
>  > Greg Rumple
>  > grumple@[...].net
>  

-- 
Greg Rumple
grumple@zaphon.llamas.net