| Subject: | Alarm Clock errors |
Hello,
Every now & again one of our perl jobs crashes with a SIGALRM, which is reported as "Alarm Clock" by the calling shell script. This only happens when downloading a https URL using the LWP library. Happens very rarely, a dozen or so occasions in a year or so of running 100 jobs a day, but or more recently now thatour system is under much higher stress.
Have a theory that the problem is in in Net::SSL::connect. (and maybe similar problem in Net::SSL::read)
The theory is that in the connect subroutine in SSL.pm it is using 'local $SIG{ALRM}' which sets the signal handler for the scope of the eval. At the end of the block is the alarm(0) to disable the alarm. Now if I understand all the signal stuff right (unlikely) then if something dies within that scope then it would jump to the end of the eval, and the signal handler would no longer be used, but the alarm is still ticking? So would it be better to have something more of the structure?
local $SIG{ALRM} = sub { $self->die_with_error("SSL read timeout") };
eval {
alaram(timeout)
....
};
alarm(0);
...
That way we are sure the alarm is being switched off, even if we fail?
Don't know if I'm talking crap or not, I'm not much of a network programmer and have no concept of the big picture. Simply narrowed down to here by grepping for calls to 'alarm' in the lib/perl tree on our server.
Let me know if I can do anything to help.
Have fun,
James
Distribution
Crypt-SSLeay-0.49 (Containing Net::SSL 2.77)
uname -a
Linux Batn04 2.4.21-4.ELsmp #1 SMP Fri Oct 3 17:52:56 EDT 2003 i686 i686 i386 GNU/Linux
perl -V
Summary of my perl5 (revision 5.0 version 8 subversion 3) configuration:
Platform:
osname=linux, osvers=2.4.21-9.elsmp, archname=i386-linux-thread-multi
uname='linux bugs.devel.redhat.com 2.4.21-9.elsmp #1 smp thu jan 8 17:08:56 est 2004 i686 i686 i386 gnulinux '
config_args='-des -Doptimize=-O2 -g -pipe -march=i386 -mcpu=i686 -Dversion=5.8.3 -Dmyhostname=localhost -Dperladmin=root@localhost -Dcc=gcc -Dcf_by=Red Hat, Inc. -Dinstallprefix=/usr -Dprefix=/usr -Darchname=i386-linux -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 -Ubincompat5005 -Uversiononly -Dpager=/usr/bin/less -isr -Dinc_version_list=5.8.2 5.8.1 5.8.0'
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', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBUGGING -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gdbm',
optimize='-O2 -g -pipe -march=i386 -mcpu=i686',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBUGGING -fno-strict-aliasing -I/usr/local/include -I/usr/include/gdbm'
ccversion='', gccversion='3.3.2 20031218 (Red Hat Linux 3.3.2-5)', 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', 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-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.3.2'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic -Wl,-rpath,/usr/lib/perl5/5.8.3/i386-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
Built under linux
Compiled at Feb 25 2004 13:30:53
@INC:
/usr/lib/perl5/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/5.8.3
/usr/lib/perl5/site_perl/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.2/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/site_perl/5.8.3
/usr/lib/perl5/site_perl/5.8.2
/usr/lib/perl5/site_perl/5.8.1
/usr/lib/perl5/site_perl/5.8.0
/usr/lib/perl5/site_perl
/usr/lib/perl5/vendor_perl/5.8.3/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.2/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.1/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.0/i386-linux-thread-multi
/usr/lib/perl5/vendor_perl/5.8.3
/usr/lib/perl5/vendor_perl/5.8.2
/usr/lib/perl5/vendor_perl/5.8.1
/usr/lib/perl5/vendor_perl/5.8.0
/usr/lib/perl5/vendor_perl