Dear Brains,

I have been using the WWW::Mechanize::Firefox module on my local machine with no complaint.

Recently I tried transferring it onto my VPS. So I made sure firefox and the MozRepl extension were installed and started both through x11 (connection speed slow but no problems to speak of). Then I attempted to run the following test script: 

#!/usr/bin/perl

use WWW::Mechanize::Firefox;
my $mech = WWW::Mechanize::Firefox->new();
$mech->get('http://www.google.com');

[download]

Not complex! However, the result is: 

MozRepl: Accepted Connection.
Segmentation fault

[download]

At first I thought it might be a simple case of not enough memory, since my VPS only has 256 MB, but free -m gives me 

             total       used       free     shared    buffers     cac
+hed
Mem:           256        226         29          0         20        
+131
-/+ buffers/cache:         74        181
Swap:          255         56        199

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In fact the used=226 is an illusion here (I think) as that figure includes the cache. I think the 74 is the actual program usage which is not that much. Further analysis with ps supports this idea - I couldn't get actual program usage to add up to more than 100 MB however I calculated it.

Next I tried running the program under gdb 

Starting program: /usr/bin/perl ./testone.pl
[Thread debugging using libthread_db enabled]
MozRepl: Accepted connection.

Program received signal SIGSEGV, Segmentation fault.
0x45978062 in ?? () from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/
+CORE/libperl.so
(gdb) bt
#0  0x45978062 in ?? () from /usr/lib/perl5/5.8.8/i386-linux-thread-mu
+lti/CORE/libperl.so
#1  0x459791d5 in ?? () from /usr/lib/perl5/5.8.8/i386-linux-thread-mu
+lti/CORE/libperl.so
#2  0x4597ac29 in Perl_sv_bless () from /usr/lib/perl5/5.8.8/i386-linu
+x-thread-multi/CORE/libperl.so
#3  0x4599ac3c in Perl_pp_bless () from /usr/lib/perl5/5.8.8/i386-linu
+x-thread-multi/CORE/libperl.so
#4  0x4596e98f in Perl_runops_standard () from /usr/lib/perl5/5.8.8/i3
+86-linux-thread-multi/CORE/libperl.so
#5  0x4590f03e in ?? () from /usr/lib/perl5/5.8.8/i386-linux-thread-mu
+lti/CORE/libperl.so
#6  0x45913906 in Perl_call_sv () from /usr/lib/perl5/5.8.8/i386-linux
+-thread-multi/CORE/libperl.so
#7  0x4597a0e4 in Perl_sv_clear () from /usr/lib/perl5/5.8.8/i386-linu
+x-thread-multi/CORE/libperl.so
#8  0x4597a945 in Perl_sv_free () from /usr/lib/perl5/5.8.8/i386-linux
+-thread-multi/CORE/libperl.so
#9  0x4597aeee in ?? () from /usr/lib/perl5/5.8.8/i386-linux-thread-mu
+lti/CORE/libperl.so
#10 0x45977d10 in ?? () from /usr/lib/perl5/5.8.8/i386-linux-thread-mu
+lti/CORE/libperl.so
#11 0x45977d7a in Perl_sv_clean_objs () from /usr/lib/perl5/5.8.8/i386
+-linux-thread-multi/CORE/libperl.so
#12 0x4591593b in perl_destruct () from /usr/lib/perl5/5.8.8/i386-linu
+x-thread-multi/CORE/libperl.so
#13 0x080491c7 in main ()
(gdb)

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And looking at the core dump: 

(gdb) core core.30048
warning: core file may not match specified executable file.
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/CORE
+/libperl.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/CORE/l
+ibperl.so
Reading symbols from /lib/libresolv.so.2...(no debugging symbols found
+)...done.
Loaded symbols for /lib/libresolv.so.2
Reading symbols from /lib/libnsl.so.1...(no debugging symbols found)..
+.done.
Loaded symbols for /lib/libnsl.so.1
Reading symbols from /lib/libdl.so.2...(no debugging symbols found)...
+done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /lib/libm.so.6...(no debugging symbols found)...d
+one.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libcrypt.so.1...(no debugging symbols found)
+...done.
Loaded symbols for /lib/libcrypt.so.1
Reading symbols from /lib/libutil.so.1...(no debugging symbols found).
+..done.
Loaded symbols for /lib/libutil.so.1
Reading symbols from /lib/libpthread.so.0...(no debugging symbols foun
+d)...done.
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /lib/libc.so.6...(no debugging symbols found)...d
+one.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib/ld-linux.so.2...(no debugging symbols found)
+...done.
Loaded symbols for /lib/ld-linux.so.2
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/Time/HiRes/HiRes.so...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/T
+ime/HiRes/HiRes.so
Reading symbols from /lib/i686/nosegneg/librt.so.1...(no debugging sym
+bols found)...done.
Loaded symbols for /lib/i686/nosegneg/librt.so.1
Reading symbols from /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-
+multi/auto/JSON/XS/XS.so...done.
Loaded symbols for /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-mu
+lti/auto/JSON/XS/XS.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/List/Util/Util.so...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/L
+ist/Util/Util.so
Reading symbols from /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-
+multi/auto/Params/Util/Util.so...done.
Loaded symbols for /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-mu
+lti/auto/Params/Util/Util.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/Cwd/Cwd.so...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/C
+wd/Cwd.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/IO/IO.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/I
+O/IO.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/Fcntl/Fcntl.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/F
+cntl/Fcntl.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/Storable/Storable.so...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/S
+torable/Storable.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/MIME/Base64/Base64.so...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/M
+IME/Base64/Base64.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/Encode/Encode.so...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/E
+ncode/Encode.so
Reading symbols from /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto
+/Socket/Socket.so...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/perl5/5.8.8/i386-linux-thread-multi/auto/S
+ocket/Socket.so
Reading symbols from /lib/libnss_files.so.2...(no debugging symbols fo
+und)...done.
Loaded symbols for /lib/libnss_files.so.2
Reading symbols from /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-
+multi/auto/Template/Stash/XS/XS.so...done.
Loaded symbols for /usr/lib/perl5/site_perl/5.8.8/i386-linux-thread-mu
+lti/auto/Template/Stash/XS/XS.so
Core was generated by `/usr/bin/perl ./testone.pl'.
Program terminated with signal 11, Segmentation fault.
#0  0x45978062 in ?? () from /usr/lib/perl5/5.8.8/i386-linux-thread-mu
+lti/CORE/libperl.so

[download]

But this is really not meaning much to me! So does anyone have any suggestions about interpreting this/what the problem might be/what to try next?

In reply to segmentation fault when trying to use mozrepl on VPS by tomgracey

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