Memory issue with get_posts( ) function

Running a no limit query is very likely the cause of your memory issues. So you might want to change your query.

If still you need to do this way, you can use the fields option, it returns post IDs only and will save a lot of memory usage – example below:

$your_query = get_posts(
    array(
        'posts_per_page' => -1,
        'post_type'      => 'post',
        'fields'         => 'ids',
    )
);