Refresh bug

[ralucasg]

Steps:
upload archive,
go to all grades,
refresh

[razvancrainea]

Additional information: this bug happened when the server was under high load and a write operation to the database (that was taking too long) was interrupted. This left the database locked for any operations, reads or writes, and the server could no longer be used.

A quick solution was to replace the database with a new one:

mv vmchecker.db vmchecker-locked.db
echo ".dump" | sqlite3 vmchecker-locked.db | sqlite3 vmchecker.db

After this the service recovered.