Bug#508914: cowdancer: cowbuilder does not separate locks in different chroots

[James Clarke]

Version: 0.47

On Mon, 23 Mar 2009 17:30:36 +0100 Stefan Fritsch  wrote:
> On Friday 19 December 2008, Junichi Uekawa wrote:
>> Ah, I think I remember something about ubuntu sudo environmental
>> variable being broken. Is LD_PRELOAD properly passed through sudo?
>> I think there was some configuration item you had to do.
> 
> Sudo is not necessary to reproduce the bug.
> 
> However upgrading to cowdancer 0.47 and pbuilder and
> 0.181 improved the situation. The build no longer fails, but there is
> still some error message about a debconf lock file.
> 
> I won't have time in the near future to investigate this further. If
> you want, you can close this bug as fixed in 0.47.

I just tried two builds running at the same time and could not reproduce this.

Regards,
James



signature.asc
Description: Message signed with OpenPGP using GPGMail

Bug#508914: cowdancer: cowbuilder does not separate locks in different chroots

[Stefan Fritsch]

On Friday 19 December 2008, Junichi Uekawa wrote:
 Ah, I think I remember something about ubuntu sudo environmental
 variable being broken. Is LD_PRELOAD properly passed through sudo?
 I think there was some configuration item you had to do.

Sudo is not necessary to reproduce the bug.

However upgrading to cowdancer 0.47 and pbuilder and 
0.181 improved the situation. The build no longer fails, but there is 
still some error message about a debconf lock file.

I won't have time in the near future to investigate this further. If 
you want, you can close this bug as fixed in 0.47.

Cheers,
Stefan



-- 
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org

Bug#508914: cowdancer: cowbuilder does not separate locks in different chroots

[Junichi Uekawa]

Ah, I think I remember something about ubuntu sudo environmental
variable being broken. Is LD_PRELOAD properly passed through sudo? I
think there was some configuration item you had to do.


At Thu, 18 Dec 2008 08:38:19 +0900,
Junichi Uekawa wrote:
 
 At Wed, 17 Dec 2008 21:21:47 +0100,
 Stefan Fritsch wrote:
  
  On Wednesday 17 December 2008, Junichi Uekawa wrote:
Package: cowdancer
Version: 0.44
  
   Why is this so old?
  
  This is actually Ubuntu hardy. I couldn't reproduce it now at home 
  with sid / 0.48 but the setup is quite different, too.
  
   I've noticed that too.
  
   What's the lock function they use?
  
  This comes from apt/libapt-pkg:
  apt-pkg/contrib/fileutl.cc:
 int FD = open(File.c_str(),O_RDWR | O_CREAT | O_NOFOLLOW,0640);
  ...
 fl.l_type = F_WRLCK;
 fl.l_whence = SEEK_SET;
 fl.l_start = 0;
 fl.l_len = 0;
 if (fcntl(FD,F_SETLK,fl) == -1)
  
  Since it does an open O_RDWR first, maybe cowdancer tried to copy the 
  file but fails? There was a cp related bug fix in 0.47. I didn't see 
  any WIFEXITED related error message, though.
  
  Do you have any idea how I could verify if it is the same bug, short 
  of installing a backported newer cowdancer?
  
 
 You should install backported cowdancer or reproduce with the latest
 version; the version in Ubuntu is not supported by anybody, 
 and later versions have additional debug messages etc.
 
 By setting COWDANCER_DEBUG environmental variable, you get more debug
 output which might or might not help.
 
  Thanks for your help.
  
  Cheers,
  Stefan
  
  
 
 



-- 
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org

Bug#508914: cowdancer: cowbuilder does not separate locks in different chroots

[Junichi Uekawa]

Hi,

At Tue, 16 Dec 2008 17:39:11 +0100,
Stefan Fritsch wrote:
 
 Package: cowdancer
 Version: 0.44

Why is this so old?

 Severity: normal
 
 When several cowbuilder instances are started in parallel, dpkg/aptitude
 in each instance will try to lock its lock file. However, since the
 files are linked across chroots, only the first succeeds and all other
 fail with
 
 Could not get lock /var/lib/dpkg/lock - open (11 Resource
 temporarily unavailable)
 
 The strace output is
 fcntl64(4, F_SETLK, {type=F_WRLCK, whence=SEEK_SET, start=0, len=0}) =
 -1 EAGAIN (Resource temporarily unavailable)
 
 As a workaround, it seems to be possible to do 
 
 rm /var/cache/pbuilder/base.cow/var/lib/dpkg/lock
 rm /var/cache/pbuilder/base.cow/var/lock/aptitude
 
 But it would be better if cowdancer would implicitly copy a file if
 a process in the chroot tries to lock it.


I've noticed that too.

What's the lock function they use?



regards,
junichi
-- 
dan...@{netfort.gr.jp,debian.org}



-- 
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org

Bug#508914: cowdancer: cowbuilder does not separate locks in different chroots

[Stefan Fritsch]

On Wednesday 17 December 2008, Junichi Uekawa wrote:
  Package: cowdancer
  Version: 0.44

 Why is this so old?

This is actually Ubuntu hardy. I couldn't reproduce it now at home 
with sid / 0.48 but the setup is quite different, too.

 I've noticed that too.

 What's the lock function they use?

This comes from apt/libapt-pkg:
apt-pkg/contrib/fileutl.cc:
   int FD = open(File.c_str(),O_RDWR | O_CREAT | O_NOFOLLOW,0640);
...
   fl.l_type = F_WRLCK;
   fl.l_whence = SEEK_SET;
   fl.l_start = 0;
   fl.l_len = 0;
   if (fcntl(FD,F_SETLK,fl) == -1)

Since it does an open O_RDWR first, maybe cowdancer tried to copy the 
file but fails? There was a cp related bug fix in 0.47. I didn't see 
any WIFEXITED related error message, though.

Do you have any idea how I could verify if it is the same bug, short 
of installing a backported newer cowdancer?

Thanks for your help.

Cheers,
Stefan



-- 
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org

Bug#508914: cowdancer: cowbuilder does not separate locks in different chroots

[Junichi Uekawa]

At Wed, 17 Dec 2008 21:21:47 +0100,
Stefan Fritsch wrote:
 
 On Wednesday 17 December 2008, Junichi Uekawa wrote:
   Package: cowdancer
   Version: 0.44
 
  Why is this so old?
 
 This is actually Ubuntu hardy. I couldn't reproduce it now at home 
 with sid / 0.48 but the setup is quite different, too.
 
  I've noticed that too.
 
  What's the lock function they use?
 
 This comes from apt/libapt-pkg:
 apt-pkg/contrib/fileutl.cc:
int FD = open(File.c_str(),O_RDWR | O_CREAT | O_NOFOLLOW,0640);
 ...
fl.l_type = F_WRLCK;
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = 0;
if (fcntl(FD,F_SETLK,fl) == -1)
 
 Since it does an open O_RDWR first, maybe cowdancer tried to copy the 
 file but fails? There was a cp related bug fix in 0.47. I didn't see 
 any WIFEXITED related error message, though.
 
 Do you have any idea how I could verify if it is the same bug, short 
 of installing a backported newer cowdancer?
 

You should install backported cowdancer or reproduce with the latest
version; the version in Ubuntu is not supported by anybody, 
and later versions have additional debug messages etc.

By setting COWDANCER_DEBUG environmental variable, you get more debug
output which might or might not help.

 Thanks for your help.
 
 Cheers,
 Stefan
 
 



-- 
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org

Bug#508914: cowdancer: cowbuilder does not separate locks in different chroots

[Stefan Fritsch]

Package: cowdancer
Version: 0.44
Severity: normal

When several cowbuilder instances are started in parallel, dpkg/aptitude
in each instance will try to lock its lock file. However, since the
files are linked across chroots, only the first succeeds and all other
fail with

Could not get lock /var/lib/dpkg/lock - open (11 Resource
temporarily unavailable)

The strace output is
fcntl64(4, F_SETLK, {type=F_WRLCK, whence=SEEK_SET, start=0, len=0}) =
-1 EAGAIN (Resource temporarily unavailable)

As a workaround, it seems to be possible to do 

rm /var/cache/pbuilder/base.cow/var/lib/dpkg/lock
rm /var/cache/pbuilder/base.cow/var/lock/aptitude

But it would be better if cowdancer would implicitly copy a file if
a process in the chroot tries to lock it.



-- 
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org