HP-UX: mdb_txn_commit and MDB_WRITEMAP

We have enabled MDB_WRITEMAP on our HP-UX 11.23 Itanium after previous discussions on the list, and that worked nicely for the most part.

However now we face a different issue: Occasionally, mdb_txn_commit will return "Resource temporarily unavailable". I have not been able to determine exactly which resource it's talking about; I suspected shared memory limits, but raising this limit did not solve the problem. This issue did not occur without MDB_WRITEMAP.

Any idea what else it could be? I can probably insert debug code into LMDB if that's needed.