[collectd] [Libguestfs] collectd leaks SIGCHLD == SIG_IGN into plugins

[Richard W.M. Jones]

On Tue, Nov 13, 2018 at 03:17:33PM +0200, Peter Dimitrov wrote:
> I was extending the virt plugin.
> It already collects similar data (about VMs) using Libvirt's API, but lacks
> disk usage information.
> 
> I went through some hoops to link libguestfs correctly to collectd.
> Is it okay to just include fork(), waitpid() example? It does reproduce the
> issue.

Yes, I think a small example/reproducer is a fine idea.

Rich.

> Best Regards,
> Peter
> 
> 
> On Tue, Nov 13, 2018 at 1:34 PM Richard W.M. Jones <rjones at redhat.com>
> wrote:
> 
> > On Tue, Nov 13, 2018 at 12:00:19PM +0100, Florian Forster wrote:
> > > Hi,
> > >
> > > thank you very much for reporting this! Sounds like a bug in the exec
> > plugin –
> > > it never ceases to amaze me how many issues a single plugin can have ;)
> > >
> > > > > > This means that any plugin that does the usual pattern of:
> > > > > >
> > > > > >   pid = fork ();
> > >
> > > Note that the exec plugin is the *only* plugin that does this. All other
> > > plugins are forbidden to fork(), popen() or create new processes in any
> > other
> > > way. The only plugin doing that, the exec plugin, has had enough issues
> > over
> > > the years for me to feel justified in that decision. ;-)
> > >
> > > As mentioned before, a Github issue would be appreciated so we can
> > properly
> > > track this problem.
> >
> > I don't know if Peter is using the exec plugin or is trying to write
> > an ordinary plugin.  However the library he is using (libguestfs)
> > certainly does fork subprocess(es).
> >
> > Rich.
> >
> > --
> > Richard Jones, Virtualization Group, Red Hat
> > http://people.redhat.com/~rjones
> > Read my programming and virtualization blog: http://rwmj.wordpress.com
> > virt-builder quickly builds VMs from scratch
> > http://libguestfs.org/virt-builder.1.html
> >

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org