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[perl #52000] Warn/abort on attempted perl exit
From:
John Gardiner Myers
Date:
March 21, 2008 18:49
Subject:
[perl #52000] Warn/abort on attempted perl exit
Message ID:
rt-3.6.HEAD-25460-1206139917-984.52000-75-0@perl.org
# New Ticket Created by John Gardiner Myers
# Please include the string: [perl #52000]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=52000 >
This is a bug report for perl from jgmyers@pong.us.proofpoint.com,
generated with the help of perlbug 1.35 running under perl v5.8.8.
-----------------------------------------------------------------
[Please enter your report here]
I have a multithreaded C++ server which embeds Perl and has a handful
of PerlInterpreter objects. One of the problems is that occasionally
Perl or some CPAN module will attempt to exit. In a multithreaded
process, calling exit() results in bad behavior--the thread will run
all of the static destructors and atexit handlers and then terminate,
leaving the remaining threads running, using the already-destructed
and/or freed static data. The process will usually dump core some
time later, possibly after having corrupted persistent data.
Clearing the PERL_EXIT_EXPECTED bit doesn't quite work right, for
reasons which I'll mention in a separate bug. One of the main
problems with it is that perl unwinds the stack a bit before even
testing for PERL_EXIT_EXPECTED, so there is no way I can find out
where in all that perl code the exit came from.
Below is a patch that adds a PERL_EXIT_WARN feature for embedders.
This allows one to obtain, through a __WARN__ handler, a perl stack
trace pointing to the code that attempted to exit.
Also is a PERL_EXIT_ABORT feature primarily intended to prevent
infinite recursion through the PERL_EXIT_WARN feature. It is also
useful separately to allow a clean abort of the process instead of
attempting to unwind the stack.
diff -u perl-5.8.8-1utf8valid/perl.c perl-5.8.8-2xexitwarn/perl.c
--- perl-5.8.8-1utf8valid/perl.c 2007-06-20 09:46:57.000000000 -0700
+++ perl-5.8.8-2xexitwarn/perl.c 2008-03-21 14:32:10.000000000 -0700
@@ -5206,6 +5206,15 @@
{
DEBUG_S(PerlIO_printf(Perl_debug_log, "my_exit: thread %p, status
%lu\n",
thr, (unsigned long) status));
+ if (PL_exit_flags & PERL_EXIT_WARN) {
+ U8 orig_exit_flags = PL_exit_flags;
+ PL_exit_flags = (PL_exit_flags | PERL_EXIT_ABORT) &
~PERL_EXIT_WARN; /* Protect against reentrant calls */
+ Perl_warn(aTHX_ "Unexpected exit %u", status);
+ PL_exit_flags = orig_exit_flags;
+ }
+ if (PL_exit_flags & PERL_EXIT_ABORT) {
+ abort();
+ }
switch (status) {
case 0:
STATUS_ALL_SUCCESS;
@@ -5246,6 +5255,15 @@
STATUS_POSIX_SET(255);
}
#endif
+ if (PL_exit_flags & PERL_EXIT_WARN) {
+ U8 orig_exit_flags = PL_exit_flags;
+ PL_exit_flags = (PL_exit_flags | PERL_EXIT_ABORT) &
~PERL_EXIT_WARN; /* Protect against reentrant calls */
+ Perl_warn(aTHX_ "Unexpected exit failure %u", PL_statusvalue);
+ PL_exit_flags = orig_exit_flags;
+ }
+ if (PL_exit_flags & PERL_EXIT_ABORT) {
+ abort();
+ }
my_exit_jump();
}
diff -u perl-5.8.8-1utf8valid/perl.h perl-5.8.8-2xexitwarn/perl.h
--- perl-5.8.8-1utf8valid/perl.h 2007-06-20 09:46:51.000000000 -0700
+++ perl-5.8.8-2xexitwarn/perl.h 2008-03-21 14:06:48.000000000 -0700
@@ -2491,6 +2491,8 @@
/* flags in PL_exit_flags for nature of exit() */
#define PERL_EXIT_EXPECTED 0x01
#define PERL_EXIT_DESTRUCT_END 0x02 /* Run END in perl_destruct */
+#define PERL_EXIT_WARN 0x04
+#define PERL_EXIT_ABORT 0x08
#ifndef MEMBER_TO_FPTR
# define MEMBER_TO_FPTR(name) name
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=medium
---
This perlbug was built using Perl v5.8.8 - Fri Mar 21 14:19:48 PDT 2008
It is being executed now by Perl v5.8.8 - Tue Feb 13 10:14:49 PST 2007.
Site configuration information for perl v5.8.8:
Configured by jgmyers at Tue Feb 13 10:14:49 PST 2007.
Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
Platform:
osname=linux, osvers=2.6.9-42.0.8.elsmp,
archname=i686-linux-thread-multi
uname='linux pong 2.6.9-42.0.8.elsmp #1 smp tue jan 30 12:33:47 est
2007 i686 i686 i386 gnulinux '
config_args=''
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=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='gcc-4.1', ccflags ='-D_REENTRANT -D_GNU_SOURCE
-DTHREADS_HAVE_PIDS -DDEBUGGING -fno-strict-aliasing -pipe
-Wdeclaration-after-statement -I/usr/local/include -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 -pipe -Wdeclaration-after-statement
-I/usr/local/include -I/usr/include/gdbm'
ccversion='', gccversion='4.1.1', 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='gcc-4.1', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=/lib/libc-2.3.4.so, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.3.4'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fpic', lddlflags='-shared -L/usr/local/lib'
Locally applied patches:
---
@INC for perl v5.8.8:
/u/jgmyers/perl/lib/5.8.8/i686-linux-thread-multi
/u/jgmyers/perl/lib/5.8.8
/u/jgmyers/perl/lib/site_perl/5.8.8/i686-linux-thread-multi
/u/jgmyers/perl/lib/site_perl/5.8.8
/u/jgmyers/perl/lib/site_perl
.
---
Environment for perl v5.8.8:
HOME=/u/jgmyers
LANG=en_US
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/tools/x/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin:/u/jgmyers/bin
PERL_BADLANG (unset)
SHELL=/bin/bash
-
[perl #52000] Warn/abort on attempted perl exit
by John Gardiner Myers