Re: pgsql: Change the way that LWLocks for extensions are allocated.

Hi,

On 2016-02-04 21:43:14 +0000, Robert Haas wrote:
> Change the way that LWLocks for extensions are allocated.
>
> The previous RequestAddinLWLocks() method had several disadvantages.
> First, the locks would be in the main tranche; we've recently decided
> that it's useful for LWLocks used for separate purposes to have
> separate tranche IDs.  Second, there wasn't any correlation between
> what code called RequestAddinLWLocks() and what code called
> LWLockAssign(); when multiple modules are in use, it could become
> quite difficult to troubleshoot problems where LWLockAssign() ran out
> of locks.  To fix, create a concept of named LWLock tranches which
> can be used either by extension or by core code.
>
> Amit Kapila and Robert Haas

I noticed that this code has no test coverage:

http://coverage.postgresql.org/src/backend/storage/lmgr/lwlock.c.gcov.html

It'd be good to add some, although I'm not entirely sure what the best
way is. Maybe add a simple pg_stat_statements test?

Andres