[prev in list] [next in list] [prev in thread] [next in thread] 

List:       perl5-porters
Subject:    [perl #31405] Nasty interaction between Reaper. Child processes, and Backticks.
From:       "Harmon S. Nine" (via RT) <perlbug-followup () perl ! org>
Date:       2004-08-31 17:22:44
Message-ID: rt-3.0.11-31405-95100.18.8437414788113 () perl ! org
[Download RAW message or body]

# New Ticket Created by  "Harmon S. Nine" 
# Please include the string:  [perl #31405]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org:80/rt3/Ticket/Display.html?id=31405 >


Hi.

This program freezes, when it should terminate almost immediately:

======================
#!/usr/bin/perl

# REAPER
$SIG{'CHLD'} = sub {
  1 while wait() != -1;
};

# CHILD PROCESS THAT NEVER ENDS
if (fork == 0) {
  sleep 60 while 1;
}

# BACKTICKS (SAME THING HAPPENS WHEN OPENING/CLOSING A PIPE WITH "open" 
AND "close")
my($my_ip) = grep { /inet addr/; } `/sbin/ifconfig eth0`;
$my_ip =~ /inet addr:(\d{1,3}(?:\.\d{1,3}){3})/;
$my_ip = $1;

# PROGRAM APPEARS TO FREEZE HERE -- THIS STATEMENT NEVER EXECUTES
print "\$my_ip = $my_ip\n";

exit 0;
======================


Here's the process listing (with 'ps -aefl'):
======================
4 S root     29002 20263  0  77   0 -   767 wait4  13:13 pts/34   
00:00:00 perl foo.pl
1 S root     29003 29002  0  75   0 -   767 -      13:13 pts/34   
00:00:00 perl foo.pl
======================


Here's the info on the perl interpreter (from Debian):
======================
r3:~# perl -V
Summary of my perl5 (revision 5 version 8 subversion 4) configuration:
  Platform:
    osname=linux, osvers=2.4.26-ti1211, archname=i386-linux-thread-multi
    uname='linux kosh 2.4.26-ti1211 #1 sat apr 24 14:46:58 est 2004 i686 
gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN 
-Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr 
-Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8 
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local 
-Dsitelib=/usr/local/share/perl/5.8.4 
-Dsitearch=/usr/local/lib/perl/5.8.4 -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 -Uusesfio -Uusenm 
-Duseshrplib -Dlibperl=libperl.so.5.8.4 -Dd_dosuid -des'
    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='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS 
-DDEBIAN -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE 
-D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN 
-fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='3.3.3 (Debian 20040429)', 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
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, 
libperl=libperl.so.5.8.4
    gnulibc_version='2.3.2'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'


Characteristics of this binary (from libperl):
  Compile-time options: MULTIPLICITY USE_ITHREADS USE_LARGE_FILES 
PERL_IMPLICIT_CONTEXT
  Built under linux
  Compiled at May 11 2004 23:53:34
  @INC:
    /etc/perl
    /usr/local/lib/perl/5.8.4
    /usr/local/share/perl/5.8.4
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.8
    /usr/share/perl/5.8
    /usr/local/lib/site_perl
    /usr/local/lib/perl/5.8.0
    /usr/local/share/perl/5.8.0
    .
r3:~#         
======================



HTH


-- Harmon S. Nine

[prev in list] [next in list] [prev in thread] [next in thread]