[rrd-developers] Limit in RRDs::graph()

Henk Uijterwaal (RIPE-NCC) henk at ripe.net
Tue Apr 29 11:14:13 MEST 2003


I have a Perl script that essentially does:

  use RRDs;

  @format = ();
  $line = 0;

  $format[$line++] = "plot.png";
  $format[$line++] = "-s $start";
  $format[$line++] = "-e $end";
  # Some formatting commands

  for ($i=0 ; $i<$MAX_TARGET ; $i++) {
    $format[$line++] = "DEF:${i}_VAL=$datadir/$i.rrd:$i:MAX";
    $format[$line++] = "CDEF:  ... ";
    $format[$line++] = "STACK ... ";

  RRDs::graph (@format);
  my $ERR=RRDs::error;
  die "ERROR: $ERR\n" if $ERR;

This works fine as long as $MAX_TARGET is small and therefor the number of
elements of @format is less than about 800.

When $MAX_TARGET becomes bigger, all entries in @format() after number 800
appear to be ignored.

It looks like I've hit some limit in RRD or its perl bindings, so I looked
for fixed size arrays and such in order to make them larger.  BUT I cannot
find anything obvious in the code that limits the number of arguments to

Anybody any ideas?


Henk Uijterwaal                             Email: henk.uijterwaal at ripe.net
RIPE Network Coordination Centre            WWW: http://www.ripe.net/home/henk
P.O.Box 10096          Singel 258           Phone: +31.20.5354414
1001 EB Amsterdam      1016 AB Amsterdam    Fax: +31.20.5354445
The Netherlands        The Netherlands      Mobile: +31.6.55861746

That problem that we weren't having yesterday, is it better? (Big ISP NOC)

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