sub svhash {      
...                                
    my ($dbhandx, $fail) = ("", ""); ##<<<<<<<<<<<<<
...
    return ($dbhandx, $fail);     ##<<<<<<<<<<<<<
}
[download]

Altering scope of $dbhandx to svhash() instead of parent module did not, unfortunately, solve the problem.

Potential nasty side effects of that mistake were never struck due to a higher level wrapper managing mutual exclusivity of processes that might clash. Lucky perhaps.