QUESTION: how to debug segfault apache1.3.22/mod_perl1.26/HTML::Mason

[Chris Hutchinson <ch...@hutchinsonsoftware.com>]

I've recently built apache 1.3.22/mod_perl 1.26, statically with perl 
5.6.1 on linux RH 7.0.

Am now getting SIGSEGV at various points in a HTML::Mason web 
application. These happen usually, but not always, when making 
DBD::Pg fetches (happens both with and without Apache::DBI).

This application was working perfectly under perl5.005, 
apache1.3.20/mod_perl 1.24!

Is there any clear way to approach solving this? I've tried tracing 
with strace (output attached below), and rebuilding everything again.

Any suggestions gratefully received, as it's getting a bit desperate here!

- Chris

strace output for _one_ of the crashing pages:
----------------------------------------------------
22372 brk(0x8957000)                    = 0x8957000
22372 read(7, "", 4096)                 = 0
22372 read(7, "", 4096)                 = 0
22372 close(7)                          = 0
22372 munmap(0x40019000, 4096)          = 0
22372 stat("/tmp/dms_cache/obj/mc/metaform_submit.mc", 
{st_mode=S_IFREG|0644, st_size=8385, ...}) = 0
22372 rt_sigaction(SIGPIPE, {SIG_IGN}, {SIG_IGN}, 8) = 0
22372 send(4, "Q SELECT Name FROM Species WHERE SpeciesID=2 \0", 46, 
0) = 46
22372 rt_sigaction(SIGPIPE, {SIG_IGN}, {SIG_IGN}, 8) = 0
22372 select(5, [4], [], [4], NULL)     = 1 (in [4])
22372 recv(4, "Pblank\0T\0\1name\0\0\0\4\23\377\377\0\0\0$D\200\0\0\0
\17E. GlobulusCSELECT\0Z", 16384, 0) = 51
22372 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
22372 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
22372 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
22372 rt_sigaction(SIGPIPE, {SIG_IGN}, {SIG_IGN}, 8) = 0
22372 send(4, "Q\n\t\t\t\tSELECT 
fieldname,label,valuesource,validsource,controltype,displayorder\n\t\t
\t\tFROM MetaForms,Meta
FormFields\n\t\t\t\tWHERE formname=\'add\' AND 
tablename=\'locationrefs\' \n\t\t\t\tAND 
metaforms.formid=metaformfields.formid
\n\t\t\t\tORDER BY displayorder ASC \0", 245, 0) = 245
22372 rt_sigaction(SIGPIPE, {SIG_IGN}, {SIG_IGN}, 8) = 0
22372 select(5, [4], [], [4], NULL)     = 1 (in [4])
22372 recv(4, "Pblank\0T\0\6fieldname\0\0\0\4\23\377\377\0\0\0hlabel\0
\0\0\4\23\377\377\0\0\0hvaluesource\0\0\0\0\31\377\377\3
77\377\377\377validsource\0\0\0\0\31\377\377\377\377\377
\377controltype\0\0\0\4\23\377\377\0\0\0\30displayorder\0\0\0\0\27\0\4
\377\377\377\377D\374\0\0\0\vbatchid\0\0\0\5.\0\0\0007
$value=Trials::getTrialEditBatch($dbi,$parent_key);\0\0\0\4\0\0\0
\10auto
\0\0\0\0050D\374\0\0\0\20lastmodified\0\0\0\0050\0\0\0\4\0\0\0\4\0\0\0
\fauto_now\0\0\0\0050D\374\0\0\0\22lastmodifiedby\0\0\0\
0050\0\0\0\22$value=$G_UID;\0\0\0\4\0\0\0\10auto\0\0\0\0050D\374\0\0\0
\vtrialid\0\0\0\0050\0\0\0\4\0\0\0\4\0\0\0\17auto_parent
\0\0\0\0050D\374\0\0\0\10name\0\0\0\10Name\0\0\0\4\0\0\0\4\0\0\0
\21text_required\0\0\0\0051D\374\0\0\0\17description\0\0\0\17D
escription\0\0\0\4\0\0\0\f$valid=1\0\0\0\ftextarea\0\0\0\0052D\374\0\0
\0\17mg"..., 16384, 0) = 805
22372 --- SIGSEGV (Segmentation fault) ---
22372 +++ killed by SIGSEGV +++
------------------------------------

Summary of my perl5 (revision 5.0 version 6 subversion 1) 
configuration:
  Platform:
    osname=linux, osvers=2.2.16-22, archname=i586-linux
    uname='linux laptop 2.2.16-22 #1 tue aug 22 16:16:55 edt 2000 
i586 unknown '
    config_args=''
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=undef use5005threads=undef useithreads=undef 
usemultiplicity=undef
    useperlio=undef d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
  Compiler:
    cc='cc', ccflags ='-fno-strict-aliasing -I/usr/local/include -
D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='2.96 20000731 (Red Hat Linux 7.0)', 
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, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lnsl -lgdbm -ldl -lm -lc -lcrypt -lutil
    perllibs=-lnsl -ldl -lm -lc -lcrypt -lutil
    libc=/lib/libc-2.1.92.so, so=so, useshrplib=false, 
libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-
rdynamic'
    cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'

Re: QUESTION: how to debug segfault apache1.3.22/mod_perl1.26/HTML::Mason

[Ged Haywood <ge...@www2.jubileegroup.co.uk>]

Hi there,

On Wed, 16 Jan 2002, Chris Hutchinson wrote:

> I've recently built apache 1.3.22/mod_perl 1.26, statically with perl 
> 5.6.1 on linux RH 7.0.
> [snip]
>     ccversion='', gccversion='2.96 20000731 (Red Hat Linux 7.0)', 

At the risk of sounding like a broken record, have you tried compiling
everyhthing with a different compiler?  The one supplied with RH7.0
had some problem (I gather:).

On a couple of RH6.2 systems I'm still using 2.91.66 with no problems,
in fact I've deliberately avoided upgrading gcc because the docs said
it wouldn't compile my kernels any more if I did...

73,
Ged.