I don't get the point of using Hash::Util::FieldHash and id_2obj though, since creating the anonymous returned by get_fds will only keep the stringified version of the object.

The point of using Hash::Util::FieldHash is that the key/value pair in a fieldhash gets automatically deallocated when its underlying object gets out of scope or is destroyed. If I would use a normal hash, and would be allocating at open, deallocating at close, I would not have the filehandles which have been successfully opened and closed and gone out of scope but not been destroyed, because there is a dangling reference to them.

The stringified filehandle object... well, that is due to indecision. If the anonymous hash returned by get_fds would sport the filehandle objects themselves, their reference count would be increased. If that returned result is not deallocated, further leakage would ensue, which would counter the whole purpose of that module. OTOH, getting a list of open filehandles for subsequent close would be a nice thing, too.

Fix for the bareword issue (also for open *STDERR etc):

    *CORE::GLOBAL::open = sub {
        my $result = $open->(@_);
        my $ref = ref $_[0] ? $_[0] : *{$_[0]}{GLOB};
        if ($result) {
            $fd{$ref}->{open} = join " ",@_,caller;
            $fd{$ref}->{opentime} = join ".", gettimeofday;
        }
        $result;
    };
    *CORE::GLOBAL::close = sub {
        my $result = $close->(@_);
        my $ref = ref $_[0] ? $_[0] : *{$_[0]}{GLOB};
        $fd{$ref}->{close} = join " ", caller;
        if ($result) {
            $fd{$ref}->{close} .= " (closed)";
        } else {
            $fd{$ref}->{close} .= " (close failed)";
        }
        $fd{$ref}->{closetime} = join ".", gettimeofday;
        $result;
    };
[download]

update: alternative class method/function get_fds:

sub get_fds {
    return  {
        map { 
            my $fd = id_2obj $_; 
            $fd => { fd => $fd, %{$fd{$_}} }
        } keys %fd 
    };
}
[download]