[mapguide-internals] MapGuide RFC 65 - ACE 5.6 upgrade is ready for review

[Traian Stanev]

About the last issue -- GDAL provider being single-threaded, it is set in the serverconfig.ini.

Simply removing the lock would not have "masked" any problem. Removing the lock AND fixing the refcounting problem in the GDAL provider itself would have made the connection pooling problems in MapGuide go away. 

The refcounting problem in the provider needs to be fixed no matter what. I can check in that fix, and remove the global GDAL lock, if you guys no longer mind. The global GDAL lock is unnecessary due to there being the global raster lock in MapGuide as well.

Traian

________________________________________
From: mapguide-internals-bounces at lists.osgeo.org [mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason Birch [Jason.Birch at nanaimo.ca]
Sent: Thursday, June 04, 2009 7:43 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] MapGuide RFC 65 - ACE 5.6 upgrade is ready    for     review

Yeah, I know, I'm whiny and conservative. :)

I don't think I was as concerned about the risk of removing the lock as I was that it would have masked an underlying deficiency in the MapGuide code, which was only emerged by the GDAL provider because it was single-threaded.  I believe that the other providers had the same problems, just with less regularity.  I also believe that Bruce's work addressed these concerns, and made MapGuide non-reliant on refcounting from the FDO providers.

If that's the case, I wouldn't have a problem with removing the MapGuide lock, which I think would then open the way to an experimental threaded GDAL provider being distributed for testing without changes to the MapGuide code.

I seem to recall that there was some other logic in MapGuide that explicitly set the raster provider to only use a single pool, but can't track it down.

Jason

-----Original Message-----
From: Traian Stanev
Sent: Thursday, June 04, 2009 4:28 PM
To: MapGuide Internals Mail List
Subject: RE: [mapguide-internals] MapGuide RFC 65 - ACE 5.6 upgrade is ready for review


It is possible to run without the lock (and also without a similar lock that exists on the other side of the GDAL provider), provided that a fix is made to the GDAL provider refcounting. This was held back for the 2.1 release due to concerns by Haris and Jason (and others) about removing the lock being risky. There was a long thread about this a month or so ago.
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