localmode, got over-size message, truncating

On 10/03/2022 12:41, Jeremy Laidman wrote:

Great work Christoph.

Sorry, it appears that I led you down the wrong path,?asserting that it 
was a server-only?setting in xymond. It would appear?to be a client-side 
setting. This seems to be undocumented in the man page for xymonclient.cfg.

Please, no worries, you steered me into the right direction and 
increasing the message sizes on the server was not a bad idea anyhow. :-)

But yes, this is undocumented unfortunately. I already filed a bug 
report with the Debian maintainers, let's see what comes of it.

Christoph

J

On Thu, 10 Mar 2022 at 21:18, Christoph Zechner <user-249716582ccc@xymon.invalid 
<mailto:user-249716582ccc@xymon.invalid>> wrote:

    I solved it!

    I had to add and set "MAXMSG_CLIENT=1024" in
    /etc/xymon/xymonclient.cfg,
    restarted xymon-client and all the errors were gone.

    Thanks again for your help!

    Cheers
    Christoph


    On 09/03/2022 06:42, Christoph Zechner wrote:

On 09/03/2022 00:04, Jeremy Laidman wrote:

On Tue, 8 Mar 2022 at 18:52, Christoph Zechner <user-249716582ccc@xymon.invalid
<mailto:user-249716582ccc@xymon.invalid <mailto:user-249716582ccc@xymon.invalid>>> wrote:

??? It seems I celebrated prematurely, the errors are back in
    exactly the
??? same way :-/

??? 2022-03-08 08:47:19.321457 Got over-size message, truncating at
528383
??? bytes (max: 524288)
??? 2022-03-08 08:47:19.339786 Dropping (more) garbled data

??? I don't understand where this limit 05 512 comes from,
    everything on
??? the
??? server checks out (2048 before, tried 4096 as well, no change).


I'm at a loss. If the xymond process is proven to have this set at
2048, then I see no reason why it would give that error message
    with
that number.

Unless it's referring to another message type and hence a different
maximum setting? Perhaps take a look at xymond's environment again,
but search for all MAXMSG_ variables. See which one is set to

    512, and

that might be the culprit. The defaults for these max values are
    all
different, with only two of them defaulting to 512: MAXMSG_CLIENT,
MAXMSG_CLICHG (reference: lib/xymond_buffer.c). But it's
    possible one
of them has been set to 512.

Thanks, I tried that, but unfortunately, this did not help, since
    all
the values were set correctly, according to my config.

The only other thing I can think of is that you have two copies of
xymond running, somehow with different values of MAXMSG_CLIENT.

    But I

can't think how this could come about. And you've already killed
    off
any rogue processes.

Right, that's not it either. :-/

Maybe run xymond in debug mode for one round of updates, until
    you get
the "Got over-size message" and review the debug logs. This might
provide enough additional detail to find out what's going on.

Another approach to solve the problem (truncated client data
    message)
is to modify the client script (eg xymonclient-linux.sh) to
    truncate
the ps command output, so that the total message size is less, and
hopefully fits within the max message size. This will mean that

    PROC

checks might not work anymore (which is likely the case now).

    But the

current state is that monitoring of the sections that come after

    [ps]

are likely broken now. On Linux this is notably the [top] and

    [vmstat]

sections of the client data message, that are used for the "cpu"
status and several metrics for graphing. Maybe something like
    adding
"head -1000" will cut it down to a reasonable size:

echo "[ps]"
ps -Aww -o
    pid,ppid,user,start,state,pri,pcpu,time,pmem,rsz,vsz,cmd |
head -1000

That's actually a gread idea and I modified the [ports] section,
    because
I know this is the culprit (running a proxy there and all the active
client connections were too much for xymon to handle.

I'm not interested in client connections anyway, I just want to
    monitor
my running programs and ports on that server, so I replaced the
    original

netstat -antuW 2>/dev/null
netstat -antuT 2>/dev/null

with

netstat -tulpenW 2>/dev/null

(adding your "| head 1000" suggestion did not work, because it
    cut off
the list before it could reach the IPv6 interfaces and thus the
    ports
check was always red).

Now xymon works again, although this is just a workaround,
    because the
underlying problem of where exactly my messages got truncated, is
    still
to be found, but I can live with this solution.

Anyway, I very much appreciate your time and efforts, thank you
    very much!

Cheers
Christoph

Also, review the client data message before the [ps] section to
    see if
there's actually something else pushing it over the limit, and [ps]
just happens to be where the truncation happens.

J

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