[mapserver-dev] Mapserver thread safety

[Andreas Albarello]

On 12.08.2013 21:44, Michel.Dastous at bentley.com wrote
> I've been testing mapserver and its c# mapscript API for a while now, and I 
> have noticed that making simultaneous Draw request on multiple maps 
> containing Oracle layer > will end up in memory corruption.  No surprise here
> since maporaclespatial.c uses static variables (ordinates_tdo and ordinates).

Michel,

aside from the static variables in maporaclespatial.c there might be another issue at play here. Especially when using an Oracle 11g client, I've found it necessary to pass both OCI_OBJECT and OCI_THREADED to OCIEnvCreate (in msOCISetHandlers). I think right now there's still only OCI_OBJECT being passed to the mode parameter of OCIEnvCreate in maporaclespatial.c. 

See also http://docs.oracle.com/cd/B28359_01/appdev.111/b28395/oci16rel001.htm#i556149 and https://forums.oracle.com/thread/575746 with the latter suggesting that one might need to use OCI_THREADED even if the application doesn't use the same environment handles across different threads which I think MapServer's connection pooling is already taking care of.

Regards,
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Andreas Albarello
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