[Xymon] xymond crashing! -- Please help!

[J.C. Cleaver]

On Sat, January 30, 2016 3:32 pm, Matt Vander Werf wrote:
> Opps...somehow sent too soon there...
>
> No, I haven't made any recent changes to client-local.cfg. I don't
> actually
> use that config for anything actually.
>
> It seems to work just fine when you're starting off with no xymond.chk
> file
> (like when the file is moved out of the way), but once the service gets
> restarted (or stopped and started), then the crashes start again and it
> becomes basically unusable. So maybe it has to do with reading the current
> state from the xymond.chk file? Or loading all the statuses?
>
> It seems to load all the statuses and then tries to set up a network
> listener and then crashes.


This is most likely the previous xymond instance still taking the network
port. After startup, xymond never re-reads the checkpoint file. If crashes
are eventually occurring even after it's started up without a checkpoint
file in place then whatever it is is occurring "live" and it's not the
checkpoint itself that's the problem.


>
> No, I'm not seeing any other error messages from xymond's startup that
> would seem related. Just that "Cannot bind to listen socket (Address
> already in use)" you saw earlier when it crashes.
>
> Are you saying I could pull data from the old xymond.chk file and manually
> put it in the current xymond.chk file when xymond is stooped? Or?

This is correct. The checkpoint file is a simple text file written out.
Actually, it might be worth a quick scan with grep or just eyeballing a
'cat' to see if there's any obviously corrupt data in there. Initial raw
messages are not binary safe, and are decompressed by xymond if needed
before internal processing, so everything there should be plain. If you
see binary garbage, something unusual has happened.

>
> Any other ideas? I'm sort of in a rut here...  :/ Not entirely sure what I
> can do to get my Xymon instance working again..
>
> Any other details I can provide that might shine a light on this issue?
>


- Can you send a copy of your client-local.cfg? Or, if not using it much,
revert it to the standard one?

- When did the issue first start?

- Based on the single backtrace, there's something strange about a client
record being pulled in, or an underlying issue with posix btrees, and/or
memory management.

Are all the crashes occurring at the same area? If so, for the same client
host message/report?

Is the main xymond server under any sort of memory pressure, or has there
been a recent glibc update or change in libraries that might require a
reboot to fully take effect?


-jc

> Thanks!!
>
> --
> Matt Vander Werf
>
> On Sat, Jan 30, 2016 at 6:05 PM, Matt Vander Werf <matt1299 at gmail.com>
> wrote:
>
>> Hi J.C.,
>>
>> No,
>>
>>
>>
>> --
>> Matt Vander Werf
>>
>> On Sat, Jan 30, 2016 at 5:46 PM, J.C. Cleaver <cleaver at terabithia.org>
>> wrote:
>>
>>>
>>> On Sat, January 30, 2016 10:45 am, Matt Vander Werf wrote:
>>> > Hi J.C.,
>>> >
>>> > So it appears that only fixed it temporarily.
>>> >
>>> > If I stop the service and start it back up again, it crashes again.
>>> >
>>> > I think I figured out how to read the core file and get a backtrace
>>> for
>>> > you
>>> > (I think).
>>> >
>>> > Here's what I got from the most recent crash (with some host names
>>> > obfuscated):
>>> >
>>> > [New LWP 13283]
>>> > Reading symbols from /usr/sbin/xymond...Reading symbols from
>>> > /usr/lib/debug/usr/sbin/xymond.debug...done.
>>> > done.
>>> > Missing separate debuginfo for
>>> > Try: yum --enablerepo='*debug*' install
>>> > /usr/lib/debug/.build-id/33/97b0d696701dbd7c09eb4bf023f7f4eebec9ed
>>> > [Thread debugging using libthread_db enabled]
>>> > Using host libthread_db library "/lib64/libthread_db.so.1".
>>> > Core was generated by `xymond --restart=/var/lib/xymon/tmp/xymond.chk
>>> > --checkpoint-file=/var/lib/xymon'.
>>> > Program terminated with signal 6, Aborted.
>>> > #0  0x00007f570e29a5f7 in raise () from /lib64/libc.so.6
>>> > Missing separate debuginfos, use: debuginfo-install
>>> > glibc-2.17-106.el7_2.1.x86_64 keyutils-libs-1.5.8-3.el7.x86_64
>>> > krb5-libs-1.13.2-10.el7.x86_64 libcom_err-1.42.9-7.el7.x86_64
>>> > libselinux-2.2.2-6.el7.x86_64 lz4-r131-1.el7.x86_64
>>> > openssl-libs-1.0.1e-51.el7_2.2.x86_64 pcre-8.32-15.el7.x86_64
>>> > xz-libs-5.1.2-12alpha.el7.x86_64 zlib-1.2.7-15.el7.x86_64
>>> > (gdb) backtrace
>>> > #0  0x00007f570e29a5f7 in raise () from /lib64/libc.so.6
>>> > #1  0x00007f570e29bce8 in abort () from /lib64/libc.so.6
>>> > #2  0x00007f570f53cdf5 in sigsegv_handler (signum=<optimized out>) at
>>> > sig.c:57
>>> > #3  <signal handler called>
>>> > #4  0x00007f570f5403b4 in xtree_i_compare (pa=0x7ffead8cb9a0,
>>> > pb=0x2020202020202020) at tree.c:47
>>> > #5  0x00007f570e3574c0 in tfind () from /lib64/libc.so.6
>>> > #6  0x00007f570f5405d4 in xtreeFind (treehandle=<optimized out>,
>>> > key=key at entry=0x7f57142cb320 "*<client hostname>*") at tree.c:140
>>> > #7  0x00007f570f5386bd in get_clientconfig
>>> > (hostname=hostname at entry=0x7f57142cb320
>>> > "*<client hostname>*", hostclass=hostclass at entry=0x7f57208e4612
>>> "linux",
>>> >     hostos=hostos at entry=0x7f57208e460c "linux") at clientlocal.c:192
>>> > #8  0x00007f570f535dec in do_message (msg=msg at entry=0x7f572064c300,
>>> > origin=origin at entry=0x7f570f550e97 "",
>>> can_respond=can_respond at entry=1)
>>> at
>>> > xymond.c:4955
>>> > #9  0x00007f570f5282c7 in main (argc=<optimized out>, argv=<optimized
>>> > out>)
>>> > at xymond.c:6288
>>> >
>>> >
>>> > Is this what you wanted? Do you want me to install the debug package
>>> for
>>> > glibc or other packages?
>>> >
>>> > Let me know what I can do.
>>> >
>>> > Thanks!!
>>>
>>> This works. It's strange in that it points to a problem with the
>>> client-local configs, but I'm not sure how the tree would get into a
>>> corrupt state.
>>>
>>> Were any changes made recently to the client-local file? Any other
>>> errors
>>> seen during xymond's startup that might seem related?
>>>
>>> It's probably *not* an issue with a status message, if they're all
>>> crashing at the same spot. This was an incoming client message that was
>>> either garbled or accessing garbled data somehow.
>>>
>>>
>>> >
>>> > --
>>> > Matt Vander Werf
>>> >
>>> > On Sat, Jan 30, 2016 at 1:10 PM, Matt Vander Werf
>>> <matt1299 at gmail.com>
>>> > wrote:
>>> >
>>> >> Hi J.C.,
>>> >>
>>> >> Moving the xymond.chk checkpoint file out of the way after it was
>>> >> stopped
>>> >> seemed to fix this (at least so far).
>>> >>
>>> >> I see that I lost all record of disabled tests (getting alerts for
>>> >> things
>>> >> that were disabled).
>>> >>
>>> >> What all data exactly did I lose with moving that checkpoint file
>>> out
>>> of
>>> >> the way?
>>> >>
>>> >> Is there anyway to get the data back? Or maybe figure out the
>>> >> corruptness
>>> >> in the checkpoint file and then move the file back in place?
>>>
>>> There are several different bits in there, including scheduled tasks,
>>> disable states, and the current status messages. You can manually copy
>>> the
>>> file back at this point while xymond is off and it will load state back
>>> from it (along with the old status messages, but they'll get
>>> overwritten
>>> as soon as the next cycle come through).
>>>
>>>
>>>
>>> >>
>>> >> Also, see my most recent e-mail with the xymonlaunch log (if you
>>> haven't
>>> >> already). Looks like this has happened in the past but resolved
>>> >> itself....
>>> >>
>>> >> Regarding the backtrace....
>>> >>
>>> >> I put those lines in /etc/sysconfig/xymonlaunch and I see the core
>>> files
>>> >> being generated now.
>>> >> I feel embarrassed to admit this, but how exactly do I get the
>>> backtrace
>>> >> out of the binary core files, besides trying to read the files with
>>> an
>>> >> editor? Any way to know which core file had the backtrace?
>>> >>
>>> >> Also, I see this in journalctl:
>>> >>
>>> >> Ignoring invalid environment assignment 'export
>>> >> DAEMON_COREFILE_LIMIT=unlimited': /etc/sysconfig/xymonlaunch
>>>
>>> Ugh. systemd :( I forgot that that's not a real shell file any more.
>>> Looks
>>> like you found a way though!
>>>
>>>
>>> -jc
>>>
>>>
>>>
>>
>