Re: hashtable crash (was Re: [PATCHES] Post-mortem: final 2PC patch)

Tom Lane wrote:

> dynahash.c thinks it should always copy 255 bytes of key, since that's
> what it was told the key size was ... but in this case the supplied
> search key has been allocated very close to the end of the process's
> memory, and there are not 255 bytes before the end of memory.

aaah - this description rings a bell ...

OpenBSD has some very useful features for configuration of malloc() -
and on this particular box it has:

G ``Guard''. Enable guard pages and chunk randomization. Each
page size or larger allocation is followed by a guard page that
will cause a segmentation fault upon any access. Smaller than
page size chunks are returned in a random order.

and indeed - enabling "G" on another (x86) OpenBSD box of mine causes
make check to die there too ....

Stefan