[ClusterLabs] Failed 'virsh' call when test RA run by crm_resource (con't)

[Keisuke MORI]

Hi,

Just a guess but could it be the same issue with this?

https://serverfault.com/questions/1105733/virsh-command-hangs-when-script-runs-in-the-background

2023年1月12日(木) 15:36 Madison Kelly <mkelly at alteeve.com>:
>
> On 2023-01-12 01:26, Reid Wahl wrote:
> > On Wed, Jan 11, 2023 at 10:21 PM Madison Kelly <mkelly at alteeve.com> wrote:
> >>
> >> On 2023-01-12 01:12, Reid Wahl wrote:
> >>> On Wed, Jan 11, 2023 at 8:11 PM Madison Kelly <mkelly at alteeve.com> wrote:
> >>>>
> >>>> Hi all,
> >>>>
> >>>>      There was a lot of sub-threads, so I figured it's helpful to start a
> >>>> new thread with a summary so far. For context; I have a super simple
> >>>> perl script that pretends to be an RA for the sake of debugging.
> >>>>
> >>>> https://pastebin.com/9z314TaB
> >>>>
> >>>>      I've had variations log environment variables and confirmed that all
> >>>> the variables in the direct call that work are in the crm_resource
> >>>> triggered call. There are no selinux issues logged in audit.log and
> >>>> selinux is permissive. The script logs the real and effective UID and
> >>>> GID and it's the same in both instances. Calling other shell programs
> >>>> (tested with 'hostname') run fine, this is specifically crm_resource ->
> >>>> test RA -> virsh call.
> >>>>
> >>>>      I ran strace on the virsh call from inside my test script (changing
> >>>> 'virsh.good' to 'virsh.bad' between running directly and via
> >>>> crm_resource. The strace runs made six files each time. Below are
> >>>> pastebin links with the outputs of the six runs in one paste, but each
> >>>> file's output is in it's own block (search for file: to see the
> >>>> different file outputs)
> >>>>
> >>>> Good/direct run of the test RA:
> >>>> - https://pastebin.com/xtqe9NSG
> >>>>
> >>>> Bad/crm_resource triggered run of the test RA:
> >>>> - https://pastebin.com/vBiLVejW
> >>>>
> >>>> Still absolutely stumped.
> >>>
> >>> The strace outputs show that your bad runs are all getting stopped
> >>> with SIGTTOU. If you've never heard of that, me either.
> >>
> >> The hell?! This is new to me also.
> >>
> >>> https://www.gnu.org/software/libc/manual/html_node/Job-Control-Signals.html
> >>>
> >>> Macro: int SIGTTOU
> >>>
> >>>       This is similar to SIGTTIN, but is generated when a process in a
> >>> background job attempts to write to the terminal or set its modes.
> >>> Again, the default action is to stop the process. SIGTTOU is only
> >>> generated for an attempt to write to the terminal if the TOSTOP output
> >>> mode is set; see Output Modes.
> >>>
> >>>
> >>> Maybe this has something to do with the buffer settings in the perl
> >>> script(?). It might be worth trying a version that doesn't fiddle with
> >>> the outputs and buffer settings.
> >>
> >> I tried removing the $|, and then I changed the script to be entirely a
> >> bash script, still hanging. I tried 'virsh --connect <method> list
> >> --all' where method was qemu:///system, qemu:///session, and
> >> ssh+qemu:///root@localhost/system, all hang. In bash or perl.
> >>
> >>> I don't know which difference between your environment and mine is
> >>> relevant here, such that I can't reproduce the issue using your test
> >>> script. It works perfectly fine for me.
> >>>
> >>> Can you run `stty -a | grep tostop`? If there's a minus sign
> >>> ("-tostop"), it's disabled; if it's present without a minus sign
> >>> ("tostop"), it's enabled, as best I can tell.
> >>
> >> -tostop is there
> >>
> >> ====
> >> [root at mk-a07n02 ~]# stty -a | grep tostop
> >> isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
> >> [root at mk-a07n02 ~]#
> >> ====
> >>
> >>> I'm just spitballing here. It's disabled by default on my machine...
> >>> but even when I enable it, crm_resource --validate works fine. It may
> >>> be set differently when running under crm_resource.
> >>
> >> How do you enable it?
> >
> > With `stty tostop`
> >
> > It's 100% possible that this whole thing is a red herring by the way.
> > I'm looking for anything that might explain the discrepancy. SIGTTOU
> > may not be directly tied to the root cause.
>
> Appreciate the stab, didn't stop the hang though :(
>
> --
> Madison Kelly
> Alteeve's Niche!
> Chief Technical Officer
> c: +1-647-471-0951
> https://alteeve.com/
>
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-- 
Keisuke MORI