Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Gunter Becker]

Hi,

I've created a new ticket:  #880   

Gunter



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Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Jackie Ng]

All MapGuide can do is open an FDO connection and set an optional timeout
beforehand. 

Any knowledge about an unreachable server is inherently FDO
provider-specific, and should be handled by the FDO provider itself. The
burden should be the FDO provider to bail immediately if it finds that its
data store is unreachable. The problem of whether it takes 1-2 minutes to
come to that conclusion is for the FDO provider to solve.

- Jackie



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Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Gunter Becker]

Hi Gabriele,

thanks for this important confirmation of this problem. If I file a bug I
will mention this issue of the OGR provider to.

Thanks, Gunter



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Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Gunter Becker]

Yes, I agree.

But could it be that there is also a problem in MapGuide? It seems that this
scenario blocks all the other FDO providers. One FDO provider shouldn't
affect the others. Isn't this handled by MapGuide itself?

Gunter



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Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Jackie Ng]

I think this is an FDO provider problem then. It should be checking for the
un-reachable server condition (if that's even possible) and bail immediately
instead of waiting for the timeout to elapse.

- Jackie



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Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Gabriele Monfardini]

Hi all,


on a side note I can confirm that the same problem also happens with OGR
Provider (we're using it to connect to PostgreSQL).

If a map is accessed with a layer that uses a non reachable PostgreSQL
(f.i. a development instance), server stops responding for a lot of time
also to other requests that belong to maps that do not reference the
problematic database.
It seems that MapGuide on the whole is waiting for timeout to expire before
serving other requests.

For a quick solution the only way is to restart MapGuide, which is
obviously problematic as expires live sessions.
I have not played with customized timeout but IMHO it seems a bug.

Regards,

Gabriele Monfardini
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Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Gunter Becker]

Hi Jackie,

it seems this only belongs to the WMS Provider and I really don't think that
this is the root problem.

So, I started further investigation and created two maps in Maestro with
some layers that references a SHP FeatureSource. In the second map I added
also a layer that references a FeatureSource to a non existent SQL Server.

When launching (preview) the second map it took approximately 1-2 min to
show up the map. The other map (without reference to SQL Server) appears
instantly.

BUT, when you try to pan or zoom the map with the SHP based layers only 
while the other map tries to reach the non existing SQL Server, then this
map hangs until the other one gets response. BTW this is the time when the
error is logged.

So, in a production environment where the connection to a SQL Server gets
lost - for what reason ever - all users would immediately notice this broken
connection even when they are accessing completely other FeatureSources in
their map.

I would expect a behavior similar to the other providers like the SHP or SDF
Provider where the broken connection is recognized immediately and an error
is logged. The map in this case also shows up instantly.

Any ideas how to fix this? I have the feeling that there already was a
similar thread in this forum in the last few weeks but I can't remember
when?

Gunter







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Re: [mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Jackie Ng]

There was a serverconfig.ini configuration property introduced some time back
to apply connection timeouts for certain FDO providers.

http://trac.osgeo.org/mapguide/ticket/1793

Whether the SQL Server FDO provider will respect whatever timeout you pass
to it. You should ask the FDO mailing list for confirmation

- Jackie



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[mapguide-users] Unavailable SQL Server hangs-up MapGuide Server

[Gunter Becker]

Hi,

we are currently using MGOS 2.4 and our customer faced some problems with a
temporarily unavailable SQL Server. Every time the SQL Server becomes
unavailable the MapGuide Server doesn't respond anymore after a short time.
It seems that the subsequent requests from users to that broken
FeatureSource causes the server to hang.

We had also some similar problems with a WMS FeatureSource hanging up the
MapGuide Server due to not accessing the WMS Service.

Does anyone had such problems in the past?
Are there any options in serverconfig.ini that can be set to ignore a no
more responding FeatureSource?

Thanks, Gunter



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