We have the exact same issue, the log file can grow to several hundreds of megabytes, containing exactly the same thing.
We also occasionally get entries like this:
[Fri Aug 19 12:14:17 2016] [9001203] [hostname] Describe SQL (DBMS)(get_column_defs)...
As far as I can tell there are no real errors in the log.
Has anyone found a solution to this problem?