I have a Web Service (in java) on a Oracle WebLogic 10.3 that does all kinds of database queries. Recently I started stress tests. It passed the repetition tests (invoke the WS several 1000 times serially) but problems become to arise when concurrency testing began. Making as much as 2 concurrent calls results in errors. When doing proper tests the results looked like the WS wasn't able to handle concurrent calls at all, which obviously should not be the case. Error included null pointer exceptions, closed connections or prepared statements, etc. I am bit stumped at this specially since I was unable to find any kind of configuration options that could effect this but then again my knowledge of the WLS is quite limited.
Thanks for any suggestions in advance.
Just so there is a clear answer.
When there are several concurrent calls to a given Web Service (in this case SOAP/JAX-WS was used) on WLS, the same object is used (no pooling or queues are used), therefore the implementation must be thread safe.
EDIT:
To clarify: Assume there is a class attribute in the WebService implementation class generated by JDeveloper. If you modify this attribute in your web method (and then use it) it will cause synchronization problems when the method is called (ie WS is called) concurrently. When I first started creating web services I though the whole WebService object was created anew for each WS call but this does not seem to be the case.