Why is ODAProvider null intermittenly?

lexthang

I'm using the BIRT model API to create reports programmatically. In the reports we create some dataset that make use of our own ODA driver. The call to create the dataset is such:

OdaDataSetHandle dsHandle = elementFactory.newOdaDataSet(name, "com.mycompany.birt.report.data.oda.dataSet");

The problem is sometimes this call returns null. But not all the time though. If we just create one report, then it is fine. If we create 5 reports in succession (ensuring they all have unique names, unique dataset names, etc), then this call only succeeds the first time, and fails (returns null) in subsequent occasions.

I tracked the failing part to this call:
ODAProvider provider = ODAProviderFactory.getInstance( ).createODAProvider(new OdaDataSet(name), "com.mycompany.birt.report.data.oda.dataSet");

When this call returns null, the dataset creation also fails.

I can't explain why this would fail intermittenly. It seems that there is something persistent (a static member or something) inside the ODA provider factory. I can't really explain what and why though.

Does anyone have any idea? Why would createODAProvider be ok the first time, but fail on subsequent calls?