>>> On 8/9/2008 at 2:22 PM, in message <[EMAIL PROTECTED]>, Carlo Marcelo
Arenas Belon <[EMAIL PROTECTED]> wrote:
> On Mon, Aug 04, 2008 at 08:40:43PM +0100, Kostas Georgiou wrote:
>>
>> I've noticed that the python scripts are always initialized even if they
>> don't have any metrics collected.
>
> right, that is a bug as the only way to "disable" a python script currently
> is
> to rename it so it won't be found by gmond.
>
> this behaviour is also inconsistent with the "C" modules as for them to be
> loaded there needs to be a configuration instructing gmond to do so, while
> python modules will load automagically even if they have no configuration to
> schedule them.
>
>> In most cases this isn't too bad
>> (assuming module_init doesn't do anything too invasive) but for example
>> tcpconn.py starts a thread running netstat that will keep running even
>> if nobody cares about the data.
>
> this is difficult to solve as it will require a redesign for the python
> metrics so they have 3 methods like the "C" modules have (init, run and
> cleanup) instead of 2 as it has now, so the init method will report which
> callback to use from gmond core to collect the metric data instead of doing
> the initialization itself.
>
>> One solution is to rename the .py files but this will not play well for
>> people using packages since they will be readded in the next package
>> update. Having a different package per plugin so they can be
>> removed/added individually is also an option if no other way to disable
>> a plugin is available.
>
> both options are just workarounds IMHO, but as you mentioned the second one
> might be the only one that is RPM friendly.
>
Actually this issue really isn't that hard solve. The python capability is all
implemented in the C module mod_python. When mod_python's init() function is
called, it simply reads the python module directory from it's configuration and
then starts a readdir() loop on that location. Anything that it finds in the
python module directory that has an extension of .py, mod_python loads and
calls the module's metric_init() function.
This behavior could be changed by simply adding a "Disabled=yes" or
"Status=disabled" type of directive to the module{} section for the python
module in it's configuration. Since gmond has already read and parsed the
entire gmond.conf including all 'included' .conf's, whether a python module is
loaded or not should be a simple matter of looking for the module{} section for
a specific module and checking to see if it is enabled or disabled. If
mod_python finds a .py file for a module but can not find a corresponding
module{} section in the configuration, the enabled status is assumed to be
'disabled' automatically. Otherwise the enabled state is assumed to be
'enabled' unless otherwise indicated. If a python module is determined to be
disabled, mod_python would not load it and obviously the python module's
metric_init() would never be called.
Does that work?
Brad
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