Re: crash with assertions and WAL_DEBUG

On 06/21/2014 01:58 PM, Heikki Linnakangas wrote:
> It's a bit difficult to attach the mark to the palloc calls, as neither
> the WAL_DEBUG or LWLOCK_STATS code is calling palloc directly, but
> marking specific MemoryContexts as sanctioned ought to work. I'll take a
> stab at that.

I came up with the attached patch. It adds a function called
MemoryContextAllowInCriticalSection(), which can be used to exempt
specific memory contexts from the assertion. The following contexts are
exempted:

* ErrorContext
* MdCxt, which is used in checkpointer to absorb fsync requests. (the
checkpointer process as a whole is no longer exempt)
* The temporary StringInfos used in WAL_DEBUG (a new memory "WAL Debug"
context is now created for them)
* LWLock stats hash table (a new "LWLock stats" context is created for it)

Barring objections, I'll commit this to master, and remove the assertion
from REL9_4_STABLE.

- Heikki