[collectd] collection.cgi reports error when processing TIME_WAIT data

[James Valente]

After further investigation, I have identified the source of the 
problem.  Apparently, rrdtool reports an error when a DEF name starting 
with the capital letters "TIME" is used in a CDEF.  This is because 
"TIME" is a special function when used in a CDEF (see the Time section 
of the rrdgraph_rpm man page).  (I am using rrdtool 1.2.12).

As a result, the use of TIME_WAIT_avg by collectd in the CDEF causes the 
following error.

    invalid rpn expression in: TIME_WAIT_avg,UN,0,TIME_WAIT_avg,IF

Solution is to rename the variable to something other than TIME_WAIT.


James Valente wrote:
> 
> When invoking the collection.cgi script, I receive the following error 
> output for each directory of "tcpconns-[portnum]-local" data.
> 
>    [Wed Oct 31 21:51:04 2007] collection.cgi: RRDs::graph:
>    invalid rpn expression in: TIME_WAIT_avg,UN,0,TIME_WAIT_avg,IF
>    at /usr/local/lighttpd/htdocs/cgi-bin/collection.cgi line 2446
> 
> The line number refers to the "if" line of code in the 
> "meta_graph_generic_stack" sub of the collection.cgi script.  (I point 
> this out, because my version of collection.cgi is slightly different 
> after I added a couple of "use lib [directory]" lines.
> 
>   RRDs::graph (@cmd);
>   if (my $errmsg = RRDs::error ())           # line 2446
>   {
>     confess ("RRDs::graph: $errmsg");
>   }
> 
> There appears to be something wrong within the tcpconns TIMW_WAIT RRD 
> files themselves.  After shutting down the collectd daemon, I then 
> deleted all TIME_WAIT files.
> 
>    rm tcpconns-*/*TIME_WAIT*
> 
> I then re-invoked the collection.cgi script successfully, with a graph 
> resulting -- albeit without any TIME_WAIT data.
> 
> I have uploaded an "rrdtool dump" version of my TIME_WAIT RRD data file 
> to the following web site.  There, you will find a complete, gzip 
> compressed version of the TIME_WAIT file, as well as a version with all 
> data points removed.
> 
>    http://www.zupercomputer.net/misc/collectd-TIME_WAIT-error/
> 
> 
> 

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