I am trying to reindex but I get an error "Stock Status Index process is working now. Please try run this process later.". When I look at
MAGENTO_ROOT/var/locks I see a ton of lock files. Some are like "index_process_7.lock" but others are like "index_process_7e7e2219-ceb3-11e5-b966-d4ae52e7d176.lock".
None of them have been modified since 2016. Is it safe to just delete them?