[xsd-users] CodeSythesis XSD - CXX Tree Multithreading issue

[tomislav.reichenbach at valida.at]

Hello,

I have a problem using CodeSythesis XSD - CXX Tree generated classes when 
using generated serialization functions from more threads.
Basically, the setup is following, the code is compiled as dlls and then 
deployed on server. The Dlls are loaded only once and upon loading the 
xercesc::XMLPlatformUtils::Initialize () is called (once). (On shutdown 
the xercesc::XMLPlatformUtils::Terminate () is called to release the 
library.) This is in line with the "3.4 Thread Safety" chapter from "
C++/Tree Mapping Getting Started Guide".

Normally everything works perfect. However, during the last/stress testing 
with particular configuration there were problems. To reproduce the 
errors, the thread count should be 20+ , and objects to be serialized 
shoud be sufficiently large (requiring more than 1s per serialization 
call). The serialized xml is then sometimes (roughly 75%) incomplete -- 
the last part is missing (not always the same tags). 

Introducing a mutex before serialization prevents errors, but I have an 
usage question, is this supposed to be so ?
To me this FAQ part is unclear :

"XSD-generated code is thread-safe in the sense that you can use different 
instantiations of the object model in several threads concurrently. This 
is possible due to the generated code not relying on any writable global 
variables. If you need to share the same object between several threads 
then you will need to provide some form of synchronization."


Per thread the order of executions is as follows:

string calculate(string input_xml) {
        input xml->istringstream->create input objects
        --- do some suff with objects ---
        output object->serialize-> output xml
        return output_xml
}
 
There are no shared (global, static or singleton) objects in the calculate 
function. 


Another remark, I have not been able to reproduce this error on my 
development machine (Core 2 Duo, winXP), only on server (4xCPU, win2003 
server).


Thanks.

Best regards



Tom