Message5748

The current implementation of org.python.core.IdImpl is not fully thread save, because the #java_obj_id(Object) method is not synchronized. IdImpl uses a java.util.HashMap to store ID-values for objects. The API-doc for java.util.HashMap requires to synchronize concurrent access to HashMap.

IdImpl.java_obj_id(Object) method is indirectly called by thread.get_ident().
(thread.get_ident() -> org.python.core.Py.java_obj_id(Object) -> org.python.core.IdImpl.java_obj_id(Object)

Django uses thread.get_ident() in its transaction management code. I observed two deadlocks on a multiprocessor server, that were apparently caused by the IdImpl#isMap HashMap being corrupted. I can provide the Java thread dumps if anybody is interested.

The attached patch fixes this issue.