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[perl #81408] Perl infinite loop: Perl_magic_get / Perl_csighandler

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Russ Weight
December 28, 2010 17:13
[perl #81408] Perl infinite loop: Perl_magic_get / Perl_csighandler
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# New Ticket Created by  Russ Weight 
# Please include the string:  [perl #81408]
# in the subject line of all future correspondence about this issue. 
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This is a bug report for perl from,
generated with the help of perlbug 1.35 running under perl v5.8.8.


We are using perl-5.8.8-32.el5_5.2.x86_64.rpm

In the context of our system test suite, we are repeatedly hitting
a hang on a perl script. We have a lot of debug statements in the
script, but output stops, sometimes in the middle of an output
string. ps shows that execution time is continuing to increase.

I attached to the running perl interpretter using gdb, and I get
the following stack trace. If I single step the code, I see a loop,
involving Perl_csighandler and Perl_magic_get. SIGSEGV is the signal
that is repeatedly occurring.

#0  0x00002b7535fc5e47 in Perl_csighandler ()
   from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/
#1  <signal handler called>
#2  0x00002b7535fca85d in Perl_magic_get ()
   from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/
#3  0x00002b7535fc97da in Perl_mg_get ()
   from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/
#4  0x00002b7535fe5baa in Perl_sv_2pv_flags ()
   from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/
#5  0x00002b7535fd4d95 in Perl_pp_concat ()
   from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/
#6  0x00002b7535fd233e in Perl_runops_standard ()
   from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/
#7  0x00002b7535f8008a in perl_run ()
   from /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE/
#8  0x00000000004017bc in main ()

We have _not_ been unable to reduce the cause to a simple test case.
If we run the test case by itself, the hang does not occur.  If we run
a subset of the test suite, the hang does not occur. The only way we
can consistently reproduce it is by running the full test suite.

We would be happy to collect additional debug information and/or run
with some test patches.

- Russ Weight

This perlbug was built using Perl v5.8.8 in the Red Hat build system.
It is being executed now by Perl v5.8.8 - Tue Sep 28 08:49:08 EDT 2010.

Site configuration information for perl v5.8.8:

Configured by Red Hat, Inc. at Tue Sep 28 08:49:08 EDT 2010.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
    osname=linux, osvers=2.6.18-53.el5, archname=x86_64-linux-thread-multi
    uname='linux 2.6.18-53.el5 #1 smp mon nov 12 02:14:55 est 2007 x86_64 x86_64 x86_64 gnulinux '
    config_args='-des -Doptimize=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -Dversion=5.8.8 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dinstallprefix=/usr -Dprefix=/usr -Dlibpth=/usr/local/lib64 /lib64 /usr/lib64 -Dprivlib=/usr/lib/perl5/5.8.8 -Dsitelib=/usr/lib/perl5/site_perl/5.8.8 -Dvendorlib=/usr/lib/perl5/vendor_perl/5.8.8 -Darchlib=/usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi -Dsitearch=/usr/lib64/perl5/site_perl/5.8.8/x86_64-linux-thread-multi -Dvendorarch=/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi -Darchname=x86_64-linux-thread-multi -Dvendorprefix=/usr -Dsiteprefix=/usr -Duseshrplib -Dusethreads -Duseithreads -Duselargefiles -Dd_dosuid -Dd_semctl_semun -Di_db -Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio -Dinstallusrbinperl=n -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr -Dd_gethostent_r_proto -Ud_end
 hostent_r_proto -Ud_sethostent_r_proto -Ud_endprotoent_r_proto -Ud_setprotoent_r_proto -Ud_endservent_r_proto -Ud_setservent_r_proto -Dinc_version_list=5.8.7 5.8.6 5.8.5 -Dscriptdir=/usr/bin'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=define use64bitall=define uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
    cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
    optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include -I/usr/include/gdbm'
    ccversion='', gccversion='4.1.2 20080704 (Red Hat 4.1.2-48)', 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='gcc', ldflags =''
    libpth=/usr/local/lib64 /lib64 /usr/lib64
    libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
    perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
    libc=, so=so, useshrplib=true,
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/CORE'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic'

Locally applied patches:

@INC for perl v5.8.8:

Environment for perl v5.8.8:
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)

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