use Proc::Governor();

    my $gov = Proc::Governor->new();

    while( ... ) {
        $gov->breathe();
        ... # Use resources
    }

    while( ... ) {
        my $res = $gov->work( sub {
            ... # Use Service
        } );
        ...
    }

##</code><code>##

    my $gov = Proc::Governor->new( {
        working     => 0,
        minSeconds  => 0.01,
        maxPercent  => 100,
        unsafe      => 0,
    } );

##</code><code>##

     H   Q   Total
    50%  0%   50%
    40% 10%   50%
    30% 20%   50%
    25% 25%   50%

##</code><code>##

    $gov->beginWork( $breathe );

##</code><code>##

    $gov->endWork( $breathe );

##</code><code>##

    $gov->work( sub {
        ... # Consume resources
    }, $which );

##</code><code>##

    $gov->beginWork( $before );
    ... # Consume resources
    $gov->endWork( $after );

##</code><code>##

    0   No pause will happen.
    1   A pause may happen before the sub reference is called.
    2   A pause may happen after the sub reference is called.
    3   A pause may happen before and/or after the sub is called.

##</code><code>##

    my @a = $gov->work( sub { ...; get_list() }, $which );
    my $s = $gov->work( sub { ...; get_item() }, $which );

##</code><code>##

    $gov->breathe( $begin );

##</code><code>##

    $gov->breathe();
    # or
    $gov->breathe( 1 );

##</code><code>##

    $gov->beginWork( 1 );

##</code><code>##

    $gov->breathe( 0 );

##</code><code>##

    $gov->pulse( $count, $begin );

##</code><code>##

    my $gov = Proc::Governor->new( {
        maxPercent  => 70,
        working     => 1,
    } );
    my $redis = Redis->new(server=>...);
    while( ... ) {
        $gov->pulse( 20 );
        $redis->...;
    }

##</code><code>##

    ...
    my $count = 0;
    while( ... ) {
        if( 20 < ++$count ) {
            $gov->breathe();
            $count = 0;
        }
        ...

##</code><code>##

    my $g_cpu = Proc::Governor->new( { maxPercent => 80 } );
    my $g_db =  Proc::Governor->new( { maxPercent => 30 } );

    $g_db->beginWork();
    my $db = DBI->connect( ... );       # DB work
    my $rows = $db->selectall_arrayref( ... );
    $g_db->endWork();

    for my $row ( @$rows ) {
        my $upd = $g_cpu->work( sub {
            process_row( $row );        # Local work
        } );
        $g_db->work( sub {
            $db->update_row( $upd );    # DB work
        } );
    }

##</code><code>##

    sub handle_request {
        my( $req ) = @_;
        our $Gov ||= Proc::Governor->new();
        my $res = $Gov->work( sub {
            forward_request( $req );
        }, 0 );                 # Don't pause here.
        give_response( $res );
        $Gov->breathe( 0 );     # Pause here; still idle.
    }