libvirt users - Nov 2012 - Handling connection closes in (older) Sys::Virt

I hope this is the correct mailing list for discussing the Sys::Virt
Perl module.

It appears that the most recent version has a new method called
register_close_callback that, I believe, can be used to catch errors
when the connection to libvirt is closed, e.g. due to libvirt restart
or a network related issue. (I've been testing this simply by killing
the the SSH process in the libvirt server.)

However, Debian still ships libvirt 0.9.12 in stable backports and
testing, as probably do many other mainstream distributions. The
latest Perl bindings that can be installed from CPAN is thus 0.9.12
and it does not have support for close callbacks. Not only that, when
a Perl program loses the (ssh) connection to libvirt, Perl just
crashes:

Program received signal SIGPIPE, Broken pipe.
0x00007ffff73de0d0 in __write_nocancel () from /lib/libpthread.so.0

Setting a?$SIG{PIPE} handler does not seem to help. Is there any
possibility of a Perl program surviving and gracefully handling a
closed libvirt connection with libvirt version 0.9.12 or
older?

Henrik

On Wed, Nov 14, 2012 at 10:15:25AM +0200, Henrik Ahlgren
wrote:
> I hope this is the correct mailing list for discussing the Sys::Virt
> Perl module.
> 
> It appears that the most recent version has a new method called
> register_close_callback that, I believe, can be used to catch errors
> when the connection to libvirt is closed, e.g. due to libvirt restart
> or a network related issue. (I've been testing this simply by killing
> the the SSH process in the libvirt server.)
> 
> However, Debian still ships libvirt 0.9.12 in stable backports and
> testing, as probably do many other mainstream distributions. The
> latest Perl bindings that can be installed from CPAN is thus 0.9.12
> and it does not have support for close callbacks. Not only that, when
> a Perl program loses the (ssh) connection to libvirt, Perl just
> crashes:
> 
> Program received signal SIGPIPE, Broken pipe.
> 0x00007ffff73de0d0 in __write_nocancel () from /lib/libpthread.so.0
> 
> Setting a?$SIG{PIPE} handler does not seem to help. Is there any
> possibility of a Perl program surviving and gracefully handling a
> closed libvirt connection with libvirt version 0.9.12 or
> older?
You definitely need to figure out how to set the SIGPIPE handler to
'ignore'. libvirt.so does not do this, because it is bad practice for
a library to set application global state like this. Not sure what
you tried, but I'd definitely expect this to work:

 $SIG{'PIPE'} = 'IGNORE';


Daniel
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