log4perl-devel

[log4perl-devel] change log level in embedded system

[Gangemi, J. <Jae...@bm...>]

hello -

  i'm currently running log4perl inside an embedded instance, for all
intents and purposes, you could say it's an environment similar to
mod_perl.

  while the system is running, i would like to send a command that changes
the log level of either the root logger or against one of the logger
categories (and potentially dynamically adding an appender so i can log to
a separate file.

  the problem i am having the log level does not persist between calls
into the system. i can make a call in and change the log level (and log a
message at the new level to make sure it worked) but on a subsequent call,
the log level has been reset to what log4perl was originally initialized
with, i.e.:

   $logger = Log::Log4perl->get_logger("");
   
   $logger->fatal("fatal message");
   $logger->trace("trace message, should not see");

   $logger->level($TRACE);
   $logger->level("trace message, should see");
  
  am i missing something w/ this idea or will i need to re-initialize
log4perl w/ a new configuration in order to make this work?

  thanks!

--
-jae

Re: [log4perl-devel] change log level in embedded system

[Mike S. <m...@pe...>]

On Tue, 17 Apr 2012, Gangemi, Jae wrote:

>  am i missing something w/ this idea or will i need to re-initialize
>  log4perl w/ a new configuration in order to make this work?

You're not saying how your call into the system works, I presume that
you're using a signal handler or some such to run a function that
manipulates the logger on a received signal. Then, somehow Log4perl gets
reinitialized by calling init() and it's back to normal. With mod_perl,
this happens e.g. when Apache starts a new child process, I suspect
something similar is happening in your embedded system.

I wonder why you're not simply using init_and_watch() and modify the
external config file to regularly check and reload it?

-- 
-- Mike

Mike Schilli
m...@pe...

> hello -
>
>  i'm currently running log4perl inside an embedded instance, for all
> intents and purposes, you could say it's an environment similar to
> mod_perl.
>
>  while the system is running, i would like to send a command that changes
> the log level of either the root logger or against one of the logger
> categories (and potentially dynamically adding an appender so i can log to
> a separate file.
>
>  the problem i am having the log level does not persist between calls
> into the system. i can make a call in and change the log level (and log a
> message at the new level to make sure it worked) but on a subsequent call,
> the log level has been reset to what log4perl was originally initialized
> with, i.e.:
>
>   $logger = Log::Log4perl->get_logger("");
>
>   $logger->fatal("fatal message");
>   $logger->trace("trace message, should not see");
>
>   $logger->level($TRACE);
>   $logger->level("trace message, should see");
>

Re: [log4perl-devel] change log level in embedded system

[Gangemi, J. <Jae...@bm...>]

  actually, no - the call into the system could be considered the
equivalent of running a cgi script inside of mod_perl, there is no signal
handler involved, but i now realize my original approach just isn't going
to work.

  the reason i'm not using 'init_and_watch()' is b/c we embed the
configuration file inside the code base (which is contained in a custom,
encrypted archive) and 'init_and_watch' only works w/ an external file,
but in order to make this work, i think i'm going to have to use some kind
of external configuration file or change how 'init_and_watch' works
locally.

  thanks!

--
-jae




On 4/17/12 9:46 PM, "Mike Schilli" <m...@pe...> wrote:

>On Tue, 17 Apr 2012, Gangemi, Jae wrote:
>
>>  am i missing something w/ this idea or will i need to re-initialize
>>  log4perl w/ a new configuration in order to make this work?
>
>You're not saying how your call into the system works, I presume that
>you're using a signal handler or some such to run a function that
>manipulates the logger on a received signal. Then, somehow Log4perl gets
>reinitialized by calling init() and it's back to normal. With mod_perl,
>this happens e.g. when Apache starts a new child process, I suspect
>something similar is happening in your embedded system.
>
>I wonder why you're not simply using init_and_watch() and modify the
>external config file to regularly check and reload it?
>
>-- 
>-- Mike
>
>Mike Schilli
>m...@pe...
>
>> hello -
>>
>>  i'm currently running log4perl inside an embedded instance, for all
>> intents and purposes, you could say it's an environment similar to
>> mod_perl.
>>
>>  while the system is running, i would like to send a command that
>>changes
>> the log level of either the root logger or against one of the logger
>> categories (and potentially dynamically adding an appender so i can log
>>to
>> a separate file.
>>
>>  the problem i am having the log level does not persist between calls
>> into the system. i can make a call in and change the log level (and log
>>a
>> message at the new level to make sure it worked) but on a subsequent
>>call,
>> the log level has been reset to what log4perl was originally initialized
>> with, i.e.:
>>
>>   $logger = Log::Log4perl->get_logger("");
>>
>>   $logger->fatal("fatal message");
>>   $logger->trace("trace message, should not see");
>>
>>   $logger->level($TRACE);
>>   $logger->level("trace message, should see");
>>

Re: [log4perl-devel] change log level in embedded system

[Mike S. <m...@pe...>]

On Wed, 18 Apr 2012, Gangemi, Jae wrote:

>  actually, no - the call into the system could be considered the
> equivalent of running a cgi script inside of mod_perl, there is no signal
> handler involved, but i now realize my original approach just isn't going
> to work.

I see, and the reset to the old configuration is related to something
within the system calling Log4perl's init()?

-- 
-- Mike

Mike Schilli
m...@pe...

>  the reason i'm not using 'init_and_watch()' is b/c we embed the
> configuration file inside the code base (which is contained in a custom,
> encrypted archive) and 'init_and_watch' only works w/ an external file,
> but in order to make this work, i think i'm going to have to use some kind
> of external configuration file or change how 'init_and_watch' works
> locally.
>
>  thanks!
>
> --
> -jae
>
>
>
>
> On 4/17/12 9:46 PM, "Mike Schilli" <m...@pe...> wrote:
>
>> On Tue, 17 Apr 2012, Gangemi, Jae wrote:
>>
>>>  am i missing something w/ this idea or will i need to re-initialize
>>>  log4perl w/ a new configuration in order to make this work?
>>
>> You're not saying how your call into the system works, I presume that
>> you're using a signal handler or some such to run a function that
>> manipulates the logger on a received signal. Then, somehow Log4perl gets
>> reinitialized by calling init() and it's back to normal. With mod_perl,
>> this happens e.g. when Apache starts a new child process, I suspect
>> something similar is happening in your embedded system.
>>
>> I wonder why you're not simply using init_and_watch() and modify the
>> external config file to regularly check and reload it?
>>
>> --
>> -- Mike
>>
>> Mike Schilli
>> m...@pe...
>>
>>> hello -
>>>
>>>  i'm currently running log4perl inside an embedded instance, for all
>>> intents and purposes, you could say it's an environment similar to
>>> mod_perl.
>>>
>>>  while the system is running, i would like to send a command that
>>> changes
>>> the log level of either the root logger or against one of the logger
>>> categories (and potentially dynamically adding an appender so i can log
>>> to
>>> a separate file.
>>>
>>>  the problem i am having the log level does not persist between calls
>>> into the system. i can make a call in and change the log level (and log
>>> a
>>> message at the new level to make sure it worked) but on a subsequent
>>> call,
>>> the log level has been reset to what log4perl was originally initialized
>>> with, i.e.:
>>>
>>>   $logger = Log::Log4perl->get_logger("");
>>>
>>>   $logger->fatal("fatal message");
>>>   $logger->trace("trace message, should not see");
>>>
>>>   $logger->level($TRACE);
>>>   $logger->level("trace message, should see");
>>>
>
>

Re: [log4perl-devel] change log level in embedded system

[Gangemi, J. <Jae...@bm...>]

  that was the idea, but now i see that's not going to work. originally i
just wanted to change the log level on the root logger, which actually did
persist (i was dumb and spaced the fact that i was bypassing the embedded
perl engine when i was testing), but that only affected the one
interpreter instance and there are many sitting in a shared pool, so that
doesn't really help my needs.

  it seems at this point, my best approach would be to figure out a way to
have the configuration be external and then use the 'init_and_watch()'
approach, sending a HUP to cause the configuration to be re-read.

--
-jae




On 4/18/12 11:29 AM, "Mike Schilli" <m...@pe...> wrote:

>On Wed, 18 Apr 2012, Gangemi, Jae wrote:
>
>>  actually, no - the call into the system could be considered the
>> equivalent of running a cgi script inside of mod_perl, there is no
>>signal
>> handler involved, but i now realize my original approach just isn't
>>going
>> to work.
>
>I see, and the reset to the old configuration is related to something
>within the system calling Log4perl's init()?
>
>-- 
>-- Mike
>
>Mike Schilli
>m...@pe...
>
>>  the reason i'm not using 'init_and_watch()' is b/c we embed the
>> configuration file inside the code base (which is contained in a custom,
>> encrypted archive) and 'init_and_watch' only works w/ an external file,
>> but in order to make this work, i think i'm going to have to use some
>>kind
>> of external configuration file or change how 'init_and_watch' works
>> locally.
>>
>>  thanks!
>>
>> --
>> -jae
>>
>>
>>
>>
>> On 4/17/12 9:46 PM, "Mike Schilli" <m...@pe...> wrote:
>>
>>> On Tue, 17 Apr 2012, Gangemi, Jae wrote:
>>>
>>>>  am i missing something w/ this idea or will i need to re-initialize
>>>>  log4perl w/ a new configuration in order to make this work?
>>>
>>> You're not saying how your call into the system works, I presume that
>>> you're using a signal handler or some such to run a function that
>>> manipulates the logger on a received signal. Then, somehow Log4perl
>>>gets
>>> reinitialized by calling init() and it's back to normal. With mod_perl,
>>> this happens e.g. when Apache starts a new child process, I suspect
>>> something similar is happening in your embedded system.
>>>
>>> I wonder why you're not simply using init_and_watch() and modify the
>>> external config file to regularly check and reload it?
>>>
>>> --
>>> -- Mike
>>>
>>> Mike Schilli
>>> m...@pe...
>>>
>>>> hello -
>>>>
>>>>  i'm currently running log4perl inside an embedded instance, for all
>>>> intents and purposes, you could say it's an environment similar to
>>>> mod_perl.
>>>>
>>>>  while the system is running, i would like to send a command that
>>>> changes
>>>> the log level of either the root logger or against one of the logger
>>>> categories (and potentially dynamically adding an appender so i can
>>>>log
>>>> to
>>>> a separate file.
>>>>
>>>>  the problem i am having the log level does not persist between calls
>>>> into the system. i can make a call in and change the log level (and
>>>>log
>>>> a
>>>> message at the new level to make sure it worked) but on a subsequent
>>>> call,
>>>> the log level has been reset to what log4perl was originally
>>>>initialized
>>>> with, i.e.:
>>>>
>>>>   $logger = Log::Log4perl->get_logger("");
>>>>
>>>>   $logger->fatal("fatal message");
>>>>   $logger->trace("trace message, should not see");
>>>>
>>>>   $logger->level($TRACE);
>>>>   $logger->level("trace message, should see");
>>>>
>>
>>