embedding and threads.pm

Sat, 01 Mar 2003 01:08:34 -0800


while debugging the modperl problem with threads.pm and not realizing that the problem lies not in the perl_clone(), but in the fact that the app itself is threaded, I was trying to reproduce the problem with one perl interpreter and its clone as you can see in the program at the end.

In the test below I'm using a blead version of the threaded perl, perl -V is at the end.

What I've noticed is that if I don't preload 'threads.pm' before cloning:

% gcc -o clone test.c `perl -MExtUtils::Embed -e ccopts -e ldopts` -Wall -g -DPRELOAD=0
% ./clone
0
1
Attempt to free temp prematurely: SV 0x810b4e4 during global destruction.
Scalars leaked: 1

I get the perl_clone report that threads->self->tid is actually 1. But I
haven't spawned any threads. Shouldn't it report 0 as its tid()?

if I compile with -DPRELOAD=1 (so the cloned perl doesn't load threads.pm), both perls report 0 as their tid.

Also I get these destruction problems/leakage report, which go away if I clone with CLONEf_KEEP_PTR_TABLE|CLONEf_COPY_STACKS contrary to what perlapi.pod's perl_clone entry suggesting to use only CLONEf_KEEP_PTR_TABLE. Is this a problem in my test program or in threads.pm?

Here is the test program:

#include <EXTERN.h>
#include <perl.h>

EXTERN_C void xs_init (pTHX);

EXTERN_C void boot_DynaLoader (pTHX_ CV* cv);

EXTERN_C void
xs_init(pTHX)
{
       char *file = __FILE__;
       dXSUB_SYS;
       /* DynaLoader is a special case */
       newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
}

#if PRELOAD == 0
#define LOAD ""
#define TEST "require threads; print threads->self->tid;"
#elif PRELOAD == 1
#define LOAD "require threads;"
#define TEST "print threads->self->tid;"
#endif

int main(int argc, char **argv, char **env)
{
    char *embedding[] = { "", "-le", "0" };
    dTHX;
    PerlInterpreter *one_perl = perl_alloc();
    PerlInterpreter *two_perl;

    aTHX = one_perl; PERL_SET_CONTEXT(aTHX);
    perl_construct(one_perl);

    perl_parse(one_perl, xs_init, 3, embedding, (char **)NULL);
    /* DynaLoader must be preloaded before perl_clone, if DynaLoader
     * is to be required later */
    eval_pv("require DynaLoader;", TRUE);
    eval_pv(LOAD, TRUE); /* loaded only by the first perl */

two_perl = perl_clone(one_perl, CLONEf_KEEP_PTR_TABLE);

eval_pv(TEST, TRUE);

    aTHX = two_perl; PERL_SET_CONTEXT(aTHX);
    eval_pv(TEST, TRUE);

    perl_destruct(two_perl);
    perl_free(two_perl);

    perl_destruct(one_perl);
    perl_free(one_perl);

exit(0);

}

perl -V:

Summary of my perl5 (revision 5.0 version 9 subversion 0 patch 18699) configuration:
Platform:
osname=linux, osvers=2.4.19-16mdksmp, archname=i686-linux-thread-multi
uname='linux hope.stason.org 2.4.19-16mdksmp #1 smp fri sep 20 16:08:37 cest 2002 i686 unknown unknown gnulinux '
config_args='-des -Dprefix=/home/stas/perl/blead-ithread -Dusethreads -Doptimize=-g -Duseshrplib -Dusedevel'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define useithreads=define usemultiplicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBUGGING -fno-strict-aliasing -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
optimize='-g',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBUGGING -fno-strict-aliasing -I/usr/include/gdbm'
ccversion='', gccversion='3.2 (Mandrake Linux 9.0 3.2-1mdk)', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -lgdbm -ldb -ldl -lm -lpthread -lc -lcrypt -lutil -lrt
perllibs=-lnsl -ldl -lm -lpthread -lc -lcrypt -lutil -lrt
libc=/lib/libc-2.3.1.so, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.3.1'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic -Wl,-rpath,/home/stas/perl/blead-ithread/lib/5.9.0/i686-linux-thread-multi/CORE'
cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'


Characteristics of this binary (from libperl):
Compile-time options: DEBUGGING MULTIPLICITY USE_ITHREADS USE_LARGE_FILES PERL_IMPLICIT_CONTEXT
Locally applied patches:
DEVEL18374
Built under linux
Compiled at Feb 14 2003 11:11:11
@INC:
/home/stas/perl/blead-ithread/lib/5.9.0/i686-linux-thread-multi
/home/stas/perl/blead-ithread/lib/5.9.0
/home/stas/perl/blead-ithread/lib/site_perl/5.9.0/i686-linux-thread-multi
/home/stas/perl/blead-ithread/lib/site_perl/5.9.0
/home/stas/perl/blead-ithread/lib/site_perl
.

__________________________________________________________________
Stas Bekman            JAm_pH ------> Just Another mod_perl Hacker
http://stason.org/     mod_perl Guide ---> http://perl.apache.org
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