Hi,
After a lot of hours I managed to trace a leak in the DBI module.
The leak is quite small, and only affects long running programms that do
a lot of queries.
consider this short program:
use DBI;
$DB = DBI->connect( 'DBI:mysql:ttt', 'root', '' ) ;
$DB->prepare("select 1") foreach ( 1..100000 );
it doesn't acctualy run anything. what it does it creates 100000s of
statement handles and then destroys them. but this also leaks exactly 16
bytes for each iteration.
if you use Devel::LeakTrace module you'll notice that it complains about
100000s of leaked RVs from DBI.pm line 1188.
on that line there is a call to _setup_handle() that is implemented in
XS.
after more digging and a lot of trial and error, it looks like the
problem is with the caching of ChildHandles.
what it actualy does it keeps a weak reference to each STH that it ever
allocates. and every 120 or so, it does some house cleaning and remove
from the array those references that are no longer valid.
the problem is that it NEVER actualy FREE those references. so they will
leak.
the attached 2 line patch will add a sv_free() to free what is no longer
needed.
Best Regards,
Doru Theodor Petrescu
diff -uBbr orig/DBI-1.51/DBI.xs DBI-1.51/DBI.xs
--- orig/DBI-1.51/DBI.xs 2006-06-06 12:49:13.000000000 +0300
+++ DBI-1.51/DBI.xs 2006-06-12 16:26:52.000000000 +0300
@@ -1069,6 +1069,8 @@
SV *sv = av_shift(av);
if (SvOK(sv))
av_push(av, sv);
+ else
+ sv_free(sv); /* keep it leak-free by Doru
Petrescu [EMAIL PROTECTED] */
}
}
}
