Can not fetch the settings from the authenticator since that is ran on a HTTP request dispatching thread where no UnitOfWork has started.It is not possible to fetch the credentials in the constructor since then it would not be possible to change the settings while the system is running. Instead recreate the client with prefetched credentials on every request.
What happens in there are simultaneous requests to open a checklist.
Both threads will read the checklist from the database, and since it
is versioned they will both get version N.
Then both threads will try to update the last open date and save the
checklist. When saving a versioned object a SQL query of the form
UPDATE checklist SET version = N+1 WHERE id = ? AND version = N
is generated, the first such query will succeed but the second one
will not update any row which Hibernate treats as an optimistic
locking error.
To work around this we use a global lock to ensure that only one
thread can update the checklist at a time. We can't use the
EntityManagers lock method since that too will cause an optimistic
locking failure. This is an unfortunate global lock that will affect
everyone even if they open different checklist, but it is such an
underused feature that it should not be a problem.
What happened was an empty list was returned if we got a bad response from the grading service. So when the check was performed "is there any examination without a grade" then it was true because there were no examinations to begin with.
Reviewers that can review in all languages will never be mismatched on language.
Added a note for projects that have not specified language to communicate with administrators doing assignment why a reviewer is classified as potentially unsuitable.
