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Jan 13, 2011, 1:22 AM
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[perl #82194] Race condition installing modules to lib in parallel builds
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# New Ticket Created by Tony Cook
# Please include the string: [perl #82194]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=82194 >
This is a bug report for perl from tony [at] develop-help,
generated with the help of perlbug 1.39 running under perl 5.13.6.
-----------------------------------------------------------------
[Please describe your issue here]
Rarely, when performing a parallel build of perl there is a race
condition between copying a module into lib/ and another process using
that module.
In smoke logs this is seen as:
File/Path.pm did not return a true value at ../../lib/AutoSplit.pm line 6.
BEGIN failed--compilation aborted at ../../lib/AutoSplit.pm line 6.
Compilation failed in require at ../../lib/ExtUtils/Install.pm line 6.
BEGIN failed--compilation aborted at ../../lib/ExtUtils/Install.pm line 6.
Compilation failed in require.
BEGIN failed--compilation aborted.
make[1]: *** [pm_to_blib] Error 255
Unsuccessful make(ext/FileCache): code=512 at make_ext.pl line 494.
make: *** [ext/FileCache/pm_to_blib] Error 25
make: *** Waiting for unfinished jobs....
File/Path.pm did not return a true value at ../../lib/AutoSplit.pm line 6.
BEGIN failed--compilation aborted at ../../lib/AutoSplit.pm line 6.
Compilation failed in require at ../../lib/ExtUtils/Install.pm line 6.
BEGIN failed--compilation aborted at ../../lib/ExtUtils/Install.pm line 6.
Compilation failed in require.
BEGIN failed--compilation aborted.
make[1]: *** [pm_to_blib] Error 255
Unsuccessful make(cpan/File-Temp): code=512 at make_ext.pl line 494.
ExtUtils/Install.pm did not return a true value.
BEGIN failed--compilation aborted.
make[1]: *** [pm_to_blib] Error 255
Unsuccessful make(cpan/ExtUtils-Manifest): code=512 at make_ext.pl line 494.
make: *** [cpan/ExtUtils-Manifest/pm_to_blib] Error 25
make: *** Waiting for unfinished jobs....
Unable to make anything but miniperl in this configuration
File/Spec.pm did not return a true value at ../../lib/File/Path.pm line 8.
BEGIN failed--compilation aborted at ../../lib/File/Path.pm line 8.
Compilation failed in require at ../../lib/AutoSplit.pm line 6.
BEGIN failed--compilation aborted at ../../lib/AutoSplit.pm line 6.
Compilation failed in require at ../../lib/ExtUtils/Install.pm line 6.
BEGIN failed--compilation aborted at ../../lib/ExtUtils/Install.pm line 6.
Compilation failed in require.
BEGIN failed--compilation aborted.
I ran a loop:
while git clean -dxf && ./Configure -des -Dusedevel && make -j6 ; do true ; done
On the 490th run:
make[1]: Entering directory `/home/tony/dev/perl/git/perl/cpan/ExtUtils-MakeMake
r'
ExtUtils/Command.pm did not return a true value.
BEGIN failed--compilation aborted.
make[1]: *** [blib/man3/.exists] Error 255
make[1]: Leaving directory `/home/tony/dev/perl/git/perl/dist/ExtUtils-ParseXS'
make config PERL_CORE=1 LIBPERL_A=libperl.a failed, continuing anyway...
Making all in dist/ExtUtils-ParseXS
make all PERL_CORE=1 LIBPERL_A=libperl.a
make[1]: Entering directory `/home/tony/dev/perl/git/perl/dist/ExtUtils-ParseXS'
make[1]: Leaving directory `/home/tony/dev/perl/git/perl/cpan/ExtUtils-Constant'
ExtUtils/Command.pm did not return a true value.
BEGIN failed--compilation aborted.
./miniperl -Ilib make_ext.pl ext/FileCache/pm_to_blib MAKE=make LIBPERL_A=libperl.a
make[1]: Leaving directory `/home/tony/dev/perl/git/perl/cpan/ExtUtils-Manifest'
Making all in cpan/ExtUtils-Manifest
make all PERL_CORE=1 LIBPERL_A=libperl.a
make[1]: Leaving directory `/home/tony/dev/perl/git/perl/dist/ExtUtils-Install'
make[1]: *** [blib/man3/.exists] Error 255
make[1]: Leaving directory `/home/tony/dev/perl/git/perl/dist/ExtUtils-ParseXS'
Unsuccessful make(dist/ExtUtils-ParseXS): code=512 at make_ext.pl line 494.
cp lib/ExtUtils/Command.pm ../../lib/ExtUtils/Command.pm
Making FileCache (all)
Creating Makefile.PL in ext/FileCache for FileCache
Running Makefile.PL in ext/FileCache
../../miniperl Makefile.PL INSTALLDIRS=perl INSTALLMAN1DIR=none INSTALLMAN3DIR=none PERL_CORE=1 LIBPERL_A=libperl.a
make: *** [dist/ExtUtils-ParseXS/pm_to_blib] Error 25
make: *** Waiting for unfinished jobs....
make[1]: Entering directory `/home/tony/dev/perl/git/perl/cpan/ExtUtils-Manifest'
cp lib/ExtUtils/MM_OS2.pm ../../lib/ExtUtils/MM_OS2.pm
cp lib/ExtUtils/MakeMaker.pm ../../lib/ExtUtils/MakeMaker.pm
cp lib/ExtUtils/MM_VOS.pm ../../lib/ExtUtils/MM_VOS.pm
cp lib/ExtUtils/MM_Unix.pm ../../lib/ExtUtils/MM_Unix.pm
cp lib/ExtUtils/Mksymlists.pm ../../lib/ExtUtils/Mksymlists.pm
<snip>
ExtUtils::Install::pm_to_blib reports the copy after performing the
copy, so it's possible here that lib/ExtUtils/Command.pm has been
created, but has only been partially copied at the point where the
other processes try to load it.
To test this, I modified ExtUtils/Install.pm:
--- a/dist/ExtUtils-Install/lib/ExtUtils/Install.pm
+++ b/dist/ExtUtils-Install/lib/ExtUtils/Install.pm
@@ -1219,8 +1219,9 @@ sub pm_to_blib {
run_filter($pm_filter, $from, $to);
print "$pm_filter <$from >$to\n";
} else {
+ print STDERR "-cp $from $to\n";
_copy( $from, $to );
- print "cp $from $to\n";
+ print STDERR "+cp $from $to\n";
}
my($mode,$atime,$mtime) = (stat $from)[2,8,9];
utime($atime,$mtime+$Is_VMS,$to);
After 209 builds I get:
+cp lib/File/Spec/Epoc.pm ../../lib/File/Spec/Epoc.pm
-cp lib/File/Spec/Cygwin.pm ../../lib/File/Spec/Cygwin.pm
+cp lib/File/Spec/Cygwin.pm ../../lib/File/Spec/Cygwin.pm
-cp lib/File/Spec.pm ../../lib/File/Spec.pm
Processing extracted/DBinaryProperties.txt
File/Spec.pm did not return a true value at ../../lib/ExtUtils/ParseXS.pm line 7
.
BEGIN failed--compilation aborted at ../../lib/ExtUtils/ParseXS.pm line 7.
Compilation failed in require at ../../lib/ExtUtils/xsubpp line 4.
BEGIN failed--compilation aborted at ../../lib/ExtUtils/xsubpp line 4.
make[1]: *** [Zlib.c] Error 255
make[1]: Leaving directory `/home/tony/dev/perl/git/perl/cpan/Compress-Raw-Zlib'
+cp lib/File/Spec.pm ../../lib/File/Spec.pm
-cp Cwd.pm ../../lib/Cwd.pm
+cp Cwd.pm ../../lib/Cwd.pm
As a further test I applied the following change locally:
--- a/dist/ExtUtils-Install/lib/ExtUtils/Install.pm
+++ b/dist/ExtUtils-Install/lib/ExtUtils/Install.pm
@@ -535,8 +535,11 @@ sub _copy {
printf "copy(%s,%s)\n", $from, $to;
}
if (!$dry_run) {
- File::Copy::copy($from,$to)
- or Carp::croak( _estr "ERROR: Cannot copy '$from' to '$to': $!" );
+ my $work = "$to.work";
+ File::Copy::copy($from,$work)
+ or Carp::croak( _estr "ERROR: Cannot copy '$from' to '$work': $!" )
+ rename($work, $to)
+ or Carp::croak( _estr "ERROR: Cannot rename '$work' to '$to': $!" );
}
}
I ran my build loop again, and killed it after 2043 successful builds.
I don't expect the change above is safe for blead:
- the extra . in filename may be a problem for some systems, or the
extra file length
- ExtUtils::Install::_copy() is also used for installion to the final
location, the change above may cause permissions problems if the
file already exists
- some (non-CORE) modules may have filenames where the .work cause a
conflict.
For a real solution:
a) some mechanism to make a non-conflicting filename
b) some mechanism to retain ownership and permissions on the target file
or
c) perhaps use copy and rename only for building the perl core
or
d) ignore the problem, it only occurs rarely
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=low
---
Site configuration information for perl 5.13.6:
Configured by tony at Sat Oct 23 11:02:59 EST 2010.
Summary of my perl5 (revision 5 version 13 subversion 6) configuration:
Derived from: 4a46fe99d0b8e1b85f7c17c5c73894e520adbf9e
Platform:
osname=linux, osvers=2.6.26-2-amd64, archname=x86_64-linux
uname='linux mars 2.6.26-2-amd64 #1 smp thu sep 16 15:56:38 utc 2010 x86_64 gnulinux '
config_args='-des -Dusedevel'
hint=recommended, useposix=true, d_sigaction=define
useithreads=undef, usemultiplicity=undef
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=define, use64bitall=define, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2',
cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.3.2', 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='cc', ldflags =' -fstack-protector -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib /lib64 /usr/lib64
libs=-lnsl -lgdbm -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
libc=/lib/libc-2.7.so, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.7'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector'
Locally applied patches:
---
@INC for perl 5.13.6:
lib
/usr/local/lib/perl5/site_perl/5.13.6/x86_64-linux
/usr/local/lib/perl5/site_perl/5.13.6
/usr/local/lib/perl5/5.13.6/x86_64-linux
/usr/local/lib/perl5/5.13.6
.
---
Environment for perl 5.13.6:
HOME=/home/tony
LANG=en_AU.UTF-8
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/home/tony/bin:/usr/local/bin:/usr/bin:/bin:/usr/games
PERL_BADLANG (unset)
SHELL=/bin/bash
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