I wrote: > One thing about ACID - IIRC there are some potential data races which my > single-word meta info in the header will fix. E.g. if the user does ^Z > at an unfortunate time, and with WRITEMAP updating the meta page while a > txn is reading it.
Reproducible by sending frequent SIGSTOPs and SIGCONTs, with mdb.c patched to verify (memcmp or checksum) the meta info after copying. Happens even with 1 MDB process. (Re comments elsewhere: Selecting a meta page is atomic, but copying/writing it is not.) -- Hallvard