Re: libpq Win32 Mutex performance patch

[Magnus Hagander <magnus(at)hagander(dot)net>]

Merlin Moncure wrote:
> On Fri, Apr 11, 2008 at 2:49 PM, Magnus Hagander
> <magnus(at)hagander(dot)net> wrote:
> > Andrew Chernow wrote:
> >  > I noticed several months ago, and came across it again today,
> >  > that libpq's pthread-win32.c implementation is using CreateMutex
> >  > rather than CRITICAL_SECTION.  CreateMutex is like a semaphore
> >  > in that it is designed to be accessible via name system-wide.
> >  > Even when you don't give it a name, thus bound to process that
> >  > created it, it still carries significant overhead compared to
> >  > using win32 CRITICAL_SECTIONs.
> >  >
> >  > The attached patch replaces the win32 mutex calls with critical
> >  > section calls.  The change will not affect the behavior of the
> >  > windows pthread_xxx functions.
> >
> >  First of all, I like this in general :-) But a couple of comments.
> >
> >  It changes the behavior when the pointer passed in is invalid from
> >  crash to silent working, right? This shouldn't actually matter,
> >  since these functions are only ever supposed to run from callers
> >  *inside libpq*, so it probalby doesn't matter...
> 
> I noticed you conjured up a ecpg threading patch sometime around early
> 2007.  You used a mutex there deliberately because that's what libpq
> did.  Maybe that patch should be adjusted?

Yes, I think it should.

//Magnus