Wrong PNG output

[human]

On a Debian Lenny system (RRDtool 1.2.27) I can reliably generate wrong PNG output out of the files attachment:delay.rrd and attachment:jitter.rrd with the following command:

sudo date -s @1213373417
rrdtool graph ntp.png --start -30h --end 1213367339 \
	--height 175 \
	"DEF:goffset=offset.rrd:42:AVERAGE" \
	"LINE2:goffset#0022ff:Offset " \
	"DEF:gjitter=jitter.rrd:42:AVERAGE" \
	"LINE2:gjitter#ff0000:Jitter "

Setting the system date at first is essential, the good and bad results have an almost 15-minute periodic pattern as described by attachment:graph.log.gz (the first column is the Unix date, the second is 1 for bad and 2 for good output).

[oetiker]

I can reproduce the problem with

 rrdtool graph ntp.png --start 1213373417-30h --end 1213367339 --height 175 "DEF:goffset=delay.rrd:42:AVERAGE" "LINE2:goffset#0022ff:Offset " "DEF:gjitter=jitter.rrd:42:AVERAGE" "LINE2:gjitter#ff0000:Jitter "

even without changing the system time ...

interestingly enough it disapers when calling

rrdtool graph ntp.png --start 1213373417-30h --end 1213367339 --height 180 "DEF:goffset=delay.rrd:42:AVERAGE" "LINE2:goffset#0022ff:Offset " "DEF:gjitter=jitter.rrd:42:AVERAGE" "LINE2:gjitter#ff0000:Jitter "

this was one of the reasons for switching to a different graphing library with rrdtool 1.3. I think we are just hitting jet another instability point in cairo here ...

is upgrading to rrdtool 1.3 an option for you ?

cheers tobi

[oetiker]

oops wanted to say libart ... not cairo!

[human]

If the rrdtool transition happens before the Debian Lenny release, then yes. :) Otherwise, I'll probably have to live with it. Not too serious, and self-curing, fortunately.

Cheers, Feri.