Re: [log4perl-devel] First Stab at Circular References

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

Kevin Goess wrote on 5/29/2004, 11:08 PM:

 > First, did you actually track down the circular reference the Logger.pm
 > mentioned?  Maybe I'm being dense (probably) but I don't see it in the
 > dump you sent. I checked out a basic $logger under use
 > Test::Memory::Cycle and didn't see any circular references.

Hmm, you could be on to someting: Maybe the reason why the loggers 
aren't cleaned up correctly isn't circular references, it's simply that 
there's still references lurking around.

They can be held by package variables like 
$Log::Log4perl::Logger::ROOT_LOGGER and also by non-lexical variables 
which have obtained a logger instance in the main program:

     no strict;
     $logger = get_logger("Foo");  # Not a "my" variable

On the other hand, if there's no circular reference, why does something 
like the following leak memory?

use Log::Log4perl qw(get_logger);

while(1) {
     Log::Log4perl->init(\ q{
log4perl.logger = DEBUG, A1
log4perl.appender.A1 = Log::Log4perl::Appender::Screen
log4perl.appender.A1.layout = SimpleLayout
});

     $logger = get_logger("foo");
}

 > So the Mail appender's DESTROY is being called during the Global
 > Destruction phase and overwriting $?.  Maybe what we need to do is
 > "local($?)" before then--if we can localize $? in the call stack above
 > where the flush() happens then the correct value will be restored after
 > the flush completes, right?

I'm not sure if you can localize $? while the GDP happens.

 > ~ However, your (Mike's) example sets $? in that BEGIN block, but doesn't
 > help Tim's code, his $? isn't from a BEGIN block.

Hmm, I didn't use a BEGIN block -- not sure I'm following.

 > However, if you change
 >     END { Log::Log4perl::Logger::cleanup(); }
 > to
 >     END { local($?); Log::Log4perl::Logger::cleanup(); }
 > Then Tim's code does finish with the proper exit strategy.

Didn't my patch work with Tim's code? I added END { $? = 255 } to Tim's 
snippet and it exited correctly with 255.

Guess we need to talk more about this, unfortunately, it's too late 
today for non-nocturnals ... :)

--
-- Mike
Mike Schilli
m...@pe...