log4perl-devel

[log4perl-devel] Can the DBIAppender Work in Multithread?

[Nan C. <cui...@gm...>]

Hi Gurus,

I'm trying to get help from you as I'm facing a problem while trying to use
the DBIAppender in multithreading code. When my code tried to create new
threads, the logger in the sub-thread body threw out exception like this:

thread failed to start: DBD::Oracle::db prepare failed: handle 2 is owned by
thread 83e0008 not current thread 8973c18 (handles can't be shared between
threads and your driver may need a CLONE method added) at
/usr/cisco/packages/perl/perl-5.8.8/lib/site_perl/5.8.8/Log/Log4perl/Appender/DBI.pm
line 88.

I'm new to Perl. I heard of that DBI is thread-safe and this might be the
root cause of this problem. But while accpting this, I still need a solution
to make the logger work also in sub-threads. I tried to share the logger,
but it came out with another error saying "(in cleanup) Can't call method
"FIRSTKEY" on an undefined value at ..... /Log/Log4perl/Logger.pm line 90
during global destruction.". And one fellow told me try to create new DBI
connection while in new thread, but I have no idea of how to do it.


Since you guys are the source, I'm turning to you. Can you guys show me a
way to my destination? Would appreciate that.


Thanks & Regards,

NC

Re: [log4perl-devel] Can the DBIAppender Work in Multithread?

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

On Thu, 14 Apr 2011, Nan Cui wrote:

> I tried to share the logger, but it came out with another error saying
> "(in cleanup) Can't call method "FIRSTKEY" on an undefined value at
> .....  /Log/Log4perl/Logger.pm line 90 during global destruction.".

Can you post a snippet of code to reproduce this problem?

-- Mike

Mike Schilli
m...@pe...

Re: [log4perl-devel] Can the DBIAppender Work in Multithread?

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

On Thu, 14 Apr 2011, Nan Cui wrote:

> When my code tried to create new
> threads, the logger in the sub-thread body threw out exception like this:
> thread failed to start: DBD::Oracle::db prepare failed: handle 2 is owned by
> thread 83e0008 not current thread 8973c18 (handles can't be shared between
> threads and your driver may need a CLONE method added) at

Hi Nan,

That might be a limitation in the Oracle driver. I'm not using Oracle
personally, but I've gotten feedback on the DBI driver being piece of
work, mainly due to the proprietary nature of the Oracle client
interface.

Anyway, if the driver doesn't allow sharing DB handles between Perl
threads, you should be able to work around the problem by explicitly
obtaining a new DB handle every time you create a new thread.

For this, you need to call the _init() method of Log4perl's DBI
appender, which you can do after retrieving the appender by name.
Something like

     Log::Log4perl->appender_by_name( "DBAppndr" )->_init();

in your consume() function should do the trick.

-- Mike

Mike Schilli
m...@pe...