| Subject: | Hanging problem on some systems |
I use Capture::Tiny's tee_merged() in an installation script to save
all output to a log file at the end of run. The installation does
various system() calls, including to apt-get etc, as well as print()-
ing messages itself. The main block of code is:
my $error;
my $output = tee_merged {
eval {
do_stuff();
do_more_stuff();
do_even_more_stuff();
do_last_stuff();
};
my $error = $@ // "";
}
write_file($log_file, ($output // "") . $error);
die $error if $error;
When installation fails and die() is called in one of the do_stuff()
routines, everything is okay.
But when installation is successful, installation hangs after
do_last_stuff(), and if I press ^C no log file is produced.
This only happens on some system, e.g. on a VirtualBox VM:
---------------------------------------------
server1:~# uname -a;perl -V
Linux server1.example.com 2.6.26-2-686 #1 SMP Sat Nov 20 23:06:30 UTC
2010 i686 GNU/Linux
Summary of my perl5 (revision 5 version 10 subversion 0) configuration:
Platform:
osname=linux, osvers=2.6.26-2-amd64, archname=i486-linux-gnu-thread-
multi
uname='linux puccini 2.6.26-2-amd64 #1 smp fri aug 14 07:12:04 utc
2009 i686 gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -
Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr -Dprivlib=/
usr/share/perl/5.10 -Darchlib=/usr/lib/perl/5.10 -Dvendorprefix=/usr -
Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/
usr/local -Dsitelib=/usr/local/share/perl/5.10.0 -Dsitearch=/usr/local/
lib/perl/5.10.0 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/
man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/
man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -
Ud_csh -Ud_ualarm -Uusesfio -Uusenm -DDEBUGGING=-g -Doptimize=-O2 -
Duseshrplib -Dlibperl=libperl.so.5.10.0 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
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='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-
aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -
D_FILE_OFFSET_BITS=64',
optimize='-O2 -g',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -
pipe -I/usr/local/include'
ccversion='', gccversion='4.3.2', 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='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib /usr/lib64
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/libc-2.7.so, so=so, useshrplib=true,
libperl=libperl.so.5.10.0
gnulibc_version='2.7'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib'
Characteristics of this binary (from libperl):
Compile-time options: MULTIPLICITY PERL_DONT_CREATE_GVSV
PERL_IMPLICIT_CONTEXT PERL_MALLOC_WRAP
USE_ITHREADS
USE_LARGE_FILES USE_PERLIO USE_REENTRANT_API
Built under linux
Compiled at Aug 28 2009 22:15:29
@INC:
/etc/perl
/usr/local/lib/perl/5.10.0
/usr/local/share/perl/5.10.0
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.10
/usr/share/perl/5.10
/usr/local/lib/site_perl
.
---------------------------------------------
This doesn't happen on another server (a physical machine), albeit with
the same OS/perl version. They are both pretty standard Debian stable.
If I do an 'strace -p' on the parent process, it hangs on waitpid() on
the child process. If I trace the child process, it hangs on read()-ing
from the file descriptor 0 (a pipe).
Regards,
Steven