DBIx::Class with Parallel::ForkManager

普通に

  my $schema = Hoge::Schema->connect(...);

  my $pfm    = Paralle::ForkManager->new(10);


  while (...) {

     $pfm->start and next;

     ...

     $pfm->finish;

  }

  $pfm->wait_all_children;

っていう普通の使い方ならうまくいくんだが、なんかの条件が重なると

  (in cleanup) Can't call method "STORE" on an undefined value at /usr/local/lib/perl5/site_perl/5.8.8/DBIx/Class/Storage/DBI.pm line 1126 during global destruction.

ってなことになる。なんでだろ。