Comment 2 for bug 820727

Reviewed: https://reviews.mahara.org/918
Committed: http://gitorious.org/mahara/mahara/commit/042f0da9f4ce0cfd4f1b2e7806fa36ca90fde541
Submitter: Richard Mansfield (<email address hidden>)
Branch: master

commit 042f0da9f4ce0cfd4f1b2e7806fa36ca90fde541
Author: Richard Mansfield <email address hidden>
Date: Fri Dec 9 14:02:09 2011 +1300

    Limit parent cache artefacts processed at one time (bug #820727)

    In commit 28599c24a22d6a5b09b972ecbd68793ce16dc7aa, the
    rebuild_artefact_parent_cache_complete cron job was rewritten to
    process artefacts in groups of 5000 owners. This limit is too high;
    I've seen the cron script run out of memory when trying to process
    ~50000 artefacts in memory at once.

    This change makes the memory usage more predictable by trying to limit
    the number of artefacts pulled into memory rather than the number of
    owners, which is often not a good approximation.

    Change-Id: If63dec213e9794e86f37461166eb0530a407e086
    Signed-off-by: Richard Mansfield <email address hidden>