No graph with a stream of constant negative numbers

[Andreas Hasenack]

Apparently I can't get this script to be plotted. Here are the details:

root@hardy-vm2:/var/log/landscape# cat /var/lib/landscape/client/custom-graph-scripts/graph-2
#!/bin/bash
echo -50
exit 0

root@hardy-vm2:/var/log/landscape# md5sum /var/lib/landscape/client/custom-graph-scripts/graph-2
fec348013265080c244b7e4bac6a05ca /var/lib/landscape/client/custom-graph-scripts/graph-2

Log:
2008-10-20 17:46:42,490 DEBUG [Dummy-1 ] Sending payload:
{'accepted-types': 'IF\x8f\xf1\xccTV\xea\x8e&\x85\xb2\xfay\x85\xeb',
 'client-api': '3.1',
 'messages': [{'api': '3.1',
               'data': {2: {'error': u'',
                            'script-hash': 'fec348013265080c244b7e4bac6a05ca',
                            'values': []}},
               'timestamp': 1224531992,
               'type': 'custom-graph'},
              {'add-processes': [{'gid': 0,
                                  'name': u'ata/0',
                                  'percent-cpu': 0.0,
                                  'pid': 1280,
                                  'start-time': 1224507518,
                                  'state': 'S',
                                  'uid': 0},
                                 {'gid': 0,
                                  'name': u'init',
                                  'percent-cpu': 0.0,
                                  'pid': 1,
                                  'start-time': 1224507515,
                                  'state': 'S',
                                  'uid': 0,
                                  'vm-size': 2844},
                                 {'gid': 0,
                                  'name': u'kthreadd',
                                  'percent-cpu': 0.0,
root@hardy-vm2:/var/log/landscape# scp broker.log
root@hardy-vm2:/var/log/landscape# cat > cg.log
2008-10-20 17:46:42,490 DEBUG [Dummy-1 ] Sending payload:
{'accepted-types': 'IF\x8f\xf1\xccTV\xea\x8e&\x85\xb2\xfay\x85\xeb',
 'client-api': '3.1',
 'messages': [{'api': '3.1',
               'data': {2: {'error': u'',
                            'script-hash': 'fec348013265080c244b7e4bac6a05ca',
                            'values': []}},
               'timestamp': 1224531992,
               'type': 'custom-graph'},
              {'add-processes': [{'gid': 0,

[Andreas Hasenack (ahasenack)]

Oops, it's landscape-client

[Thomas Herve (therve)]

There is nothing in the graph that can confirm nor deny the problem actually: the client does send empty values if the 5 minutes loop has ended (and it generally takes 2 loops to send values). If there is a problem, there should be a traceback somewhere?

[Andreas Hasenack (ahasenack)]

Ah, if all problems had tracebacks, this would be so much easier :)

I did another attempt, starting from scratch and using trunk r67 this time instead of that custom-graph-client branch (I was using r83 of it).

The CG script was created at 21:07. Now it's 21h50 and there are still no data points in the graph. I also reduced the interval from the default 5min to 60s in customgraph.py and I created some activities in between to try to trigger a data exchange.

The client now is showing it's sending the points upwards:

# grep values /var/log/landscape/broker.log
                            'values': []}},
                            'values': [(1224544140, -50.0)]}},
                            'values': [(1224544200, -50.0)]}},
                            'values': [(1224544260, -50.0)]}},
                            'values': [(1224544320, -50.0)]}},
                            'values': [(1224544380, -50.0)]}},
(...)

There are 48 "values" lines there as of this moment (21h57).

[Thomas Herve (therve)]

What do you mean "no data points in the graph"? There is nothing in the site, or nothing in the database?

The log you pasted seems to show that the client is doing the right thing.

[Andreas Hasenack (ahasenack)]

This is what I mean. Notice that the scale didn't even change, it's still the default 0 -> 1.

Note also that the machines were off during the night, so the last data point would be from around 22h last night. After that I don't expect anything to show up.

[Andreas Hasenack (ahasenack)]

So, after some testing and debugging, these are the conclusions:

- r836 of custom-graph-display-errors fixes plotting of negative numbers, but see below

- a constant stream of negative numbers will only be plotted once there was some variation. So, a CG script of "echo -50" will never get the value "-50" plotted. There has to be at least one data point different than "-50", then the whole thing is plotted

- a constant stream of *positive* numbers, though, is always plotted without issues

Looks like a RRDtool bug so far.

[Andreas Hasenack (ahasenack)]

It works with newer versions of rrdtool (hardy has 1.2.19). The changeset that fixed it for me is:

http://oss.oetiker.ch/rrdtool-trac/changeset/1233

I'm attaching a script which shows the problem and can be used to test the fix. When run with the buggy version of rrdtool installed, it will not graph the data (constant -50). With the fixed version, the line is drawn.

[Andreas Hasenack (ahasenack)]

It's not a bug in the client, and the client is not affected by it.

[Andreas Hasenack (ahasenack)]

Nothing we can do on the Landscape side

[Clint Byrum (clint-fewbar)]

Marking as fix released in ubuntu's rrdtool. This is too minor of an issue for an SRU to dapper, and it seems the patch above is already applied to hardy and later.