BerkeleyDB and Perl, lock not removed if crashed

I have a Perl script which I'm using with BerkeleyDB.

I want to make sure the database is locked whilst I read it or write to it.

I wrote some code that worked fine, but had a problem where if one part was crashed whilst it held a lock then the lock was never removed (I had to delete the files created by BerkeleyDB and start again to remove it).

I have now created some code to test this with.

One piece of code aquires a lock and then just sits in a loop forever. The other one tries to write to the database.

What I want to happen is that when the first piece of code is crashed the second one is then able to continue, but this isn't the case.

Can someone please tell me what I need to do to achieve this.

Code A
 
use BerkeleyDB;
use FindBin qw($Bin);
 
my $d_rsync = "$Bin/data/plugin-rsync.ydb";
 
#load the database
my $dbEnv;
unless ( $dbEnv = BerkeleyDB::Env -> new ( -Home => "$Bin/data" , -Flags  => DB_CREATE | DB_INIT_CDB | DB_INIT_MPOOL ) ) {
	Log ( $l_db , "failed to load database enviroment.\nReason: $BerkeleyDB::Error" );
	exit;
}
 
#load the data into a hash
my %rData;
my $hDb;
unless ( $hDb = tie %rData , 'BerkeleyDB::Hash' , { -Filename => $d_rsync , -Flags => DB_CREATE , -Env => $dbEnv } ) {
	Log ( $l_db , "failed to load database \'$d_rsync\'.\nReason: $BerkeleyDB::Error" );
	exit;
}
 
#acquire a read lock on the database
my $lock = $hDb -> cds_lock();
 
while (1) {
	sleep (1);
}
exit;
 
 
 
Code B
 
use BerkeleyDB;
use FindBin qw($Bin);
 
my $d_rsync = "$Bin/data/plugin-rsync.ydb";
 
#load the database
my $dbEnv;
unless ( $dbEnv = BerkeleyDB::Env -> new ( -Home => "$Bin/data" , -Flags  => DB_CREATE | DB_INIT_CDB | DB_INIT_MPOOL ) ) {
	Log ( $l_db , "failed to load database enviroment.\nReason: $BerkeleyDB::Error" );
	exit;
}
 
#load the data into a hash
my %rData;
my $hDb;
unless ( $hDb = tie %rData , 'BerkeleyDB::Hash' , { -Filename => $d_rsync , -Flags => DB_CREATE , -Env => $dbEnv } ) {
	Log ( $l_db , "failed to load database \'$d_rsync\'.\nReason: $BerkeleyDB::Error" );
	exit;
}
 
#acquire a write lock on the database
my $lock = $hDb -> cds_lock();
my $lCursor = $hDb -> db_cursor ( DB_WRITECURSOR );
 
#set the status in the database
$rData{'state'} = 'Scanning';
 
#remove the lock
$lCursor -> c_close();
$lock -> cds_unlock();

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