If the process of rebuilding the index gets interupted by a shutdown or restart of Confluence, it doesn't fininsh reindexing on the next startup.

This is particulary affecting upgrades where we sometimes need to trigger a rebuild of the index. If that task fails it is never retriggered again which leaves Confluence in an inconsistent state after the upgrade.

A solution would be to keep a marker file somewhere as soon as the reindexing is started and only remove it once the reindexing is finished. That way we can restart the indexing on startup if such a file is present.