Looks fine. You ssem to be using the same flags that I use. Using the transactions and page-level locking is a mistake for most applications, since it requires you to handle deadlocks and makes everything more complex.

Here's some sample code:

  my %Cache;
  my $env = new BerkeleyDB::Env(
      -Home  => '/tmp',
      -Flags => DB_INIT_CDB | DB_CREATE | DB_INIT_MPOOL,
      )
      or die "can't create BerkelyDB::Env: $!";
  my $Obj = tie %Cache, 'BerkeleyDB::Btree',
     -Filename => '/tmpfs/bdbfile',
     -Flags    => DB_CREATE,
     -Mode     => 0640,
     -Env      => $env
     or die ("Can't tie to /tmp/bdbdfile: $!");
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I use the db_get/db_put calls with this, and no explicit locking, and it scales very well.