Breakdown in build system

[Fabian Huch]

> When issuing a new build task, the resulting URL (e.g. 
> https://build.proof.cit.tum.de/build?id=ce0149bb-3b02-41f1-8a65-cf00e4bc0720) 
> just yields »Invalid request« and the task doesn’t show up in 
> https://build.proof.cit.tum.de/home
>
> What is going wrong here?

The database connection had been closed:

> Exception in thread "Isabelle.thread-15" Exception in thread 
> "Isabelle.thread-18" org.postgresql.util.PSQLException: This 
> connection has been closed.

But I don't see a reason for that: The database is still running.

We do have problems with long-running SSH connections (the nightly 
presentation job regularly fails because of SSH disconnects), but so far 
the database connections have not created any problems. I have to 
investigate this at some point: Perhaps we have to build a mechanism for 
re-connects when the underlying connections are not perfectly reliable.


Fabian