Division by Zero

[ccogdill]

I am having a problem with division by zero when I create new graphs for any host. I have traced the problem down to switching the poller interval from one minute to five minutes. When the poller interval is set to one minute everything is fine. However, when I set the poller interval to 5 minutes that is when I receive the following error. Can someone please help with this? Is it a bug in Cacti or am I doing something wrong? I have searched and searched the forums but no luck.

ERROR MESSAGE:
-----------------------------------
Warning: Division by zero in /opt/cacti/lib/api_poller.php on line 119

Warning: Cannot modify header information - headers already sent by (output started at /opt/cacti/lib/api_poller.php:119) in /opt/cacti/graphs_new.php on line 323

CRONTAB SETTINGS:
---------------------------------------
Crontab used with one minute poller:
* * * * * /opt/php/bin/php /opt/cacti/poller.php > /dev/null 2>&1

Crontab used with five minute poller setting:
0,5,10,15,20,25,30,35,40,45,50,55 * * * * /opt/php/bin/php /opt/cacti/poller.php > /dev/null 2>&1

I have also tried this one as well
5,10,15,20,25,30,35,40,45,50,55 * * * * /opt/php/bin/php /opt/cacti/poller.php > /dev/null 2>&1


ENVIRONMENT
---------------------------
OS: Solaris 10 update 5
Apache 2.2.8
PHP 5.2.5
libxml 2.6.31
MySQL 5.0.51a
rrdtool 1.2.x
Cacti 0.8.7b (with settings 0.5 and thold 0.3.9
Spine 0.8.7a
Perl 5.10.0

[TheWitness]

It looks as though poller.php is not creating a session file to maintain variable state. The error message seems to indicate that the variable $poller_interval is uninitialized, which it should not be due to the fact that it is initialized in the following:

Code: Select all

$poller_interval = read_config_option("poller_interval")

A few lines before. You should attempt to patch Cacti. Goto the web site and look at the current patches for 0.8.7b. I think there is one in there specific to this problem maybe. Not 100% sure. It's definitely configuration related though.

TheWitness

[nduda78]

I am in the same boat here...

[TheWitness]

Make sure you are running 0.8.7b and not "a".

TheWitness

[nduda78]

I am running 8.7b with all patches

[TheWitness]

This may be PHP specific. Try the modified code below and see if the error goes away. Please post updates here.

Code: Select all

		if ($modulus == 0) {
			$rrd_next_step = 0;
		}else{
			$rrd_next_step = $poller_interval * ($rrd_step_counter % $modulus);

TheWitness

[nduda78]

This may be PHP specific. Try the modified code below and see if the error goes away. Please post updates here.

Code: Select all

		if ($modulus == 0) {
			$rrd_next_step = 0;
		}else{
			$rrd_next_step = $poller_interval * ($rrd_step_counter % $modulus);

TheWitness

Thanks Witness, I'll try as soon as I get into work in 30min or so. What file is that, not that it matters I can grep for the text.

[nduda78]

I get this when i try to reindex with your changes:
Parse error: syntax error, unexpected $end in /www/htdocs/cacti/lib/api_poller.php on line 145

Here is what api_poller.php looks like:

<?php
/*
+-------------------------------------------------------------------------+
| Copyright (C) 2004-2008 The Cacti Group |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public License |
| as published by the Free Software Foundation; either version 2 |
| of the License, or (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
+-------------------------------------------------------------------------+
| Cacti: The Complete RRDTool-based Graphing Solution |
+-------------------------------------------------------------------------+
| This code is designed, written, and maintained by the Cacti Group. See |
| about.php and/or the AUTHORS file for specific developer information. |
+-------------------------------------------------------------------------+
| http://www.cacti.net/ |
+-------------------------------------------------------------------------+
*/

function api_poller_cache_item_add($host_id, $host_field_override, $local_data_id, $rrd_step, $poller_action_id, $data_source_item_name, $num_rrd_items, $arg1 = "", $arg2 = "", $arg3 = "") {
$host = db_fetch_row("select
host.id,
host.hostname,
host.snmp_community,
host.snmp_version,
host.snmp_username,
host.snmp_password,
host.snmp_auth_protocol,
host.snmp_priv_passphrase,
host.snmp_priv_protocol,
host.snmp_context,
host.snmp_port,
host.snmp_timeout,
host.disabled
from host
where host.id=$host_id");

/* the $host_field_override array can be used to override certain host fields in the poller cache */
if (isset($host)) {
$host = array_merge($host, $host_field_override);
}

if (isset($host["id"]) || (isset($host_id))) {
if (isset($host)) {
if ($host["disabled"] == "on") {
return true;
}
} else {
if ($poller_action_id == 0) {
return true;
}

$host["id"] = 0;
$host["snmp_community"] = "";
$host["snmp_timeout"] = "";
$host["snmp_username"] = "";
$host["snmp_password"] = "";
$host["snmp_auth_protocol"] = "";
$host["snmp_priv_passphrase"] = "";
$host["snmp_priv_protocol"] = "";
$host["snmp_context"] = "";
$host["snmp_version"] = "";
$host["snmp_port"] = "";
$host["hostname"] = "None";
}

if ($poller_action_id == 0) {
if (($host["snmp_version"] < 1) || ($host["snmp_version"] > 3) ||
($host["snmp_community"] == "" && $host["snmp_version"] != 3)) {
return true;
}
}

$rrd_next_step = api_poller_get_rrd_next_step($rrd_step, $num_rrd_items);

return db_execute("INSERT INTO poller_item (local_data_id, host_id, action,hostname,
snmp_community, snmp_version, snmp_timeout, snmp_username, snmp_password,
snmp_auth_protocol, snmp_priv_passphrase, snmp_priv_protocol, snmp_context, snmp_port, rrd_name, rrd_path,
rrd_num, rrd_step, rrd_next_step, arg1, arg2, arg3)
VALUES
($local_data_id, " . $host["id"] . ", $poller_action_id,'" . $host["hostname"] . "',
'" . $host["snmp_community"] . "', '" . $host["snmp_version"] . "', '" . $host["snmp_timeout"] . "',
'" . $host["snmp_username"] . "', '" . $host["snmp_password"] . "', '" . $host["snmp_auth_protocol"] . "',
'" . $host["snmp_priv_passphrase"] . "', '" . $host["snmp_priv_protocol"] . "', '" . $host["snmp_context"] . "',
'" . $host["snmp_port"] . "', '$data_source_item_name', '" . addslashes(clean_up_path(get_data_source_path($local_data_id, true))) . "',
'$num_rrd_items', '$rrd_step', '$rrd_next_step', '$arg1', '$arg2', '$arg3')");
}
}

function api_poller_get_rrd_next_step($rrd_step=300, $num_rrd_items=1) {
global $config;

$poller_interval = read_config_option("poller_interval");
$rrd_next_step = 0;
if (($rrd_step != $poller_interval) && (isset($poller_interval))){
if (!isset($config["rrd_step_counter"])) {
$rrd_step_counter = read_config_option("rrd_step_counter");
}else{
$rrd_step_counter = $config["rrd_step_counter"];
}

if ($num_rrd_items == 1) {
$config["rrd_num_counter"] = 0;
}else{
if (!isset($config["rrd_num_counter"])) {
$config["rrd_num_counter"] = 1;
}else{
$config["rrd_num_counter"]++;
}
}

$modulus = $rrd_step / $poller_interval;

if ($modulus == 0) {
$rrd_next_step = 0;
}else{
$rrd_next_step = $poller_interval * ($rrd_step_counter % $modulus);

if ($num_rrd_items == 1) {
$rrd_step_counter++;
}else{
if ($num_rrd_items == $config["rrd_num_counter"]) {
$rrd_step_counter++;
$config["rrd_num_counter"] = 0;
}
}

if ($rrd_step_counter >= $modulus) {
$rrd_step_counter = 0;
}

/* save rrd_step_counter */
$config["rrd_step_counter"] = $rrd_step_counter;
db_execute("replace into settings (name, value) values ('rrd_step_counter','$rrd_step_counter')");
}

return $rrd_next_step;
}
?>

[TheWitness]

Sorry missed

Code: Select all

}

at the end.

TheWitness

[nduda78]

No go...re-indexing works, but rebuilding poller cache spits out:
Warning: Division by zero in /www/htdocs/cacti/lib/api_poller.php on line 122

[igorx]

Try php code

Code: Select all

<?php print 3 % 0.5;?>

You get the error "div by zero". Only integer divider must be used with operator '%'

Code: Select all

if ($modulus<1) { 
         $rrd_next_step = 0; 
      }else{ 
         $rrd_next_step = $poller_interval * ($rrd_step_counter % $modulus);
}