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lib/AI/MXNet/KVStore.pm  view on Meta::CPAN

=head2  num_workers

    Get the number of worker nodes

    Returns
    -------
    size :int
        The number of worker nodes
=cut

method num_workers()
{
    return scalar(check_call(AI::MXNetCAPI::KVStoreGetGroupSize($self->handle)));
}

=head2 save_optimizer_states

    Save optimizer (updater) state to file

    Parameters
    ----------
    fname : str
        Path to output states file.
=cut

method save_optimizer_states(Str $fname)
{
    confess("Cannot save states for distributed training")
        unless defined $self->_updater;
    open(F, ">:raw", "$fname") or confess("can't open $fname for writing: $!");
    print F $self->_updater->get_states();
    close(F);
}

=head2 load_optimizer_states

    Load optimizer (updater) state from file.

    Parameters
    ----------
    fname : str
        Path to input states file.
=cut

method load_optimizer_states(Str $fname)
{
    confess("Cannot save states for distributed training")
        unless defined $self->_updater;
    open(F, "<:raw", "$fname") or confess("can't open $fname for reading: $!");
    my $data;
    { local($/) = undef; $data = <F>; }
    close(F);
    $self->_updater->set_states($data);
}

=head2 _set_updater

    Set a push updater into the store.

    This function only changes the local store. Use set_optimizer for
    multi-machines.

    Parameters
    ----------
    updater : function
        the updater function

    Examples
    --------
    >>> my $update = sub { my ($key, input, stored) = @_;
        ...     print "update on key: $key\n";
        ...     $stored += $input * 2; };
        >>> $kv->_set_updater($update)
        >>> $kv->pull(3, out=>$a)
        >>> print $a->aspdl()
        [[ 4.  4.  4.]
        [ 4.  4.  4.]]
        >>> $kv->push(3, mx->nd->ones($shape))
        update on key: 3
        >>> $kv->pull(3, out=>$a)
        >>> print $a->aspdl()
        [[ 6.  6.  6.]
        [ 6.  6.  6.]]
=cut

method _set_updater(CodeRef $updater_func)
{
    $self->_updater_func(
        sub {
            my ($index, $input_handle, $storage_handle) = @_;
            $updater_func->(
                $index,
                AI::MXNet::NDArray->new(handle => $input_handle),
                AI::MXNet::NDArray->new(handle => $storage_handle)
            );
        }
    );
    check_call(
        AI::MXNetCAPI::KVStoreSetUpdater(
            $self->handle,
            $self->_updater_func
        )
    );
}

=head2 _barrier

    Global barrier between all worker nodes.

    For example, assume there are n machines, we want to let machine 0 first
    init the values, and then pull the inited value to all machines. Before
    pulling, we can place a barrier to guarantee that the initialization is
    finished.
=cut

method _barrier()
{
    check_call(AI::MXNetCAPI::KVStoreBarrier($self->handle));
}