1. Problem Description:
While developing with CGI::Application and utilizing Apache::Reload, we
encountered an issue where our modules were not being succesfully
reinitialized on reload. It was traced down to @ISA not containing the
proper values after a 'use base' directive, but only on automatic
reload, and freshly on perl 5.10, not our previous version of perl 5.8.8!
I determined that when ModPerl::Util::unload_package is used to unload a
package, when it is then re-required in perl 5.10, 'use base' directives
don't function as expected.
I recreated the problem with this simple use case. It happens when a
sub-module (required by something else) is unloaded then re-required. I
included the workaround using the push @ISA method to contrast working
with not working.
This is the output when the program below is run.
$ perl t.pl
X
X
V
Not a CODE reference at t.pl line 14.
Where did the inheritance go after the require of v? Is this a bug in
the do-file functionality utilized by require? Did
ModPerl::Util::unload_package not do something it was supposed to? Is
there a subtle interaction between 5.10 and ModPerl::Util?
I was initially going to submit this to the perl bug database, but
realized that the unload_package function was a ModPerl functionality,
so this is my first place to go. Five files to test with itemized
below. As you can see, I can recreate it without utilizing the mod_perl
environment specifically.
--- begin t.pl ---
#!/usr/bin/perl
use ModPerl::Util;
# Using push @ISA
require w;
w->x();
ModPerl::Util::unload_package('w');
require w;
w->x();
# Using use base
require u;
u->v();
ModPerl::Util::unload_package('v');
require u;
u->v();
-- end t.pl --
--- begin u.pm ---
package u;
use v;
use base 'v';
1;
--- end u.pm
--- begin v.pm ---
package v;
sub v { print "V\n";}
1;
--- end v.pm
--- begin w.pm ---
package w;
use x;
BEGIN { push @ISA, 'x'; }
1;
--- end w.pm
--- begin x.pm ---
package x;
sub x { print "X\n";}
1;
--- end x.pm
2. Used Components and their Configuration:
*** mod_perl version 2.000004
*** using /usr/lib/perl5/Apache2/BuildConfig.pm
*** Makefile.PL options:
MP_APR_LIB => aprext
MP_APXS => /usr/bin/apxs2
MP_CCOPTS => -g -Wall
MP_COMPAT_1X => 1
MP_GENERATE_XS => 1
MP_INCLUDE_DIR => /usr/include/apache2 /usr/include/apr-1.0
MP_LIBNAME => mod_perl
MP_TRACE => 0
MP_USE_DSO => 1
MP_USE_GTOP => 1
MP_USE_STATIC => 0
*** The httpd binary was not found
*** (apr|apu)-config linking info
-L/usr/lib -laprutil-1
-L/usr/lib -lapr-1 -luuid -lrt -lcrypt -lpthread -ldl
*** /usr/bin/perl -V
Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
Platform:
osname=linux, osvers=2.6.24-16-server,
archname=x86_64-linux-gnu-thread-multi
uname='linux yellow 2.6.24-16-server #1 smp thu apr 10 13:15:38 utc
2008 x86_64 gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.10.0
-Dsitearch=/usr/local/lib/perl/5.10.0 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio
-Uusenm -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib
-Dlibperl=libperl.so.5.10.0 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
useithreads=define, usemultiplicity=define
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=define, use64bitall=define, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN
-fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
optimize='-O2 -g',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing
-pipe -I/usr/local/include'
ccversion='', gccversion='4.3.2', gccosandvers=''
intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
alignbytes=8, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/libc-2.8.90.so, so=so, useshrplib=true,
libperl=libperl.so.5.10.0
gnulibc_version='2.8.90'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib'
Characteristics of this binary (from libperl):
Compile-time options: MULTIPLICITY PERL_DONT_CREATE_GVSV
PERL_IMPLICIT_CONTEXT PERL_MALLOC_WRAP
USE_64_BIT_ALL
USE_64_BIT_INT USE_ITHREADS USE_LARGE_FILES
USE_PERLIO USE_REENTRANT_API
Built under linux
Compiled at Dec 23 2008 02:55:19
%ENV:
PERL_LWP_USE_HTTP_10="1"
@INC:
/etc/perl
/usr/local/lib/perl/5.10.0
/usr/local/share/perl/5.10.0
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.10
/usr/share/perl/5.10
/usr/local/lib/site_perl
.
*** Packages of interest status:
Apache2 : -
Apache2::Request : -
CGI : 3.29
ExtUtils::MakeMaker: 6.42, 6.48
LWP : 5.812
mod_perl : -
mod_perl2 : 2.000004
3. This is the core dump trace: (if you get a core dump):
Not relevant
This report was generated by /usr/share/libapache2-mod-perl2/mp2bug on
Sat Dec 27 01:11:46 2008 GMT.
---
David Ihnen
Perl Programmer
Norchem Laboratories, Inc
