Function batch_with_pool 

pub fn batch_with_pool<P, F, R>(
    pool: &ExifToolPool,
    items: Vec<P>,
    processor: F,
) -> Vec<Result<R>> 
where
    P: Send + 'static,
    F: Fn(&mut ExifTool, P) -> Result<R> + Send + Sync + 'static,
    R: Send + 'static,

批量处理使用连接池